USB Printer not connecting in Juno

Question: Under Loki, my HP LaserJet 1012 connected and worked without any setup or issues but under Juno it doesn't seem to want to connect. Any ideas on how to get it working? I tried the add a printer button but it didn't seem to want to work afterwards.
Comment: Where did you try it before?
Comment: I'm not sure what you're asking. I just backed up my data and did a nuke and pave on the same system to upgrade from Loki to Juno and now my printer doesn't work where it did before. Same printer, same computer, same USB connection. I've tried disconnecting/reconnecting and turning the printer off/on as well as the aforementioned add printer button in the printer menu (and interestingly enough it does see the printer there but it doesn't print after I select it) and nothing. It doesn't let me print anything.
Comment: I was asking what OS you where using before. But you just told me anyway. Try to add your printer directly from cups: open a web browser and type: `http://localhost:631/`  then fiddle with the settings.
Comment: I'm not trying to print from a network, I'm trying to print from the local computer. The printer isn't showing up in the printer menu at all.
Comment: It doesn't matter. That link opens a configuration page for CUPS. From there you can do anything related to your computer.
Answer: I found a fix. I manually added the printer using the + button on the printer menu in Settings and finding it in the list, then enabled it and set it as default. Then I opened the terminal and used lpq to configure it.
The commands I used are:
lpq enable
lpq up
Then I was able to print from LibreOffice without issues.
Answer: I just reinstalled the laptop from Loki to Juno...
I got the problem with that my phone is not charging anymore when i will connect the cable to the laptop.
What happens - i will connect the phone to the usb, phone will show charging, juno will show the accessible device in device-list of files, ...and in one second phone is disconnected from power and stop charging. When i will click in device list to open this phone, it will "mount" the phone even if the phone is selected to "charging mode" and in that moment phone is charging again.
I think it is the same issue with your printer.
Probably Juno will try to read-up the connected device for a second and after that it is turning off the powersupply to device... :/

USB Printer not connecting in Juno


Is every bra vector the complex conjugate of ket vector?

Question: $\renewcommand{\ket}[1]{\lvert #1 \rangle}\renewcommand{\bra}[1]{\langle #1 \rvert}$Suppose we are taking the inner product of two vectors, say $a$ and $b$ as
$$\bra{a}b\rangle$$
where $\bra{a}$ is a bra vector and $\ket{b}$ is a ket vector.
Is it important that every time we do inner product we do it for a vector and its complex conjugate or we can take inner product of any two vectors? Does it always mean that $\bra{a}$ is complex conjugate of $\ket{b}$ whenever we are taking an inner product?
Answer: The inner product is always between two (ket) vectors. However, let $\mathcal H$ be the space in which they live. This is a complex vector space with a Hermitian inner product. The inner product defines a map $\mathcal H\to\mathcal H^\vee$, where $\mathcal H^\vee$ is the dual of $\mathcal H$, and consists of linear functionals on $\mathcal H$. The map is given by $a\mapsto a^\ast$ which is defined by $a^\ast(b) = \langle a,b\rangle$.
In fact the inner product defines a metric on $\mathcal H$ and the postulates of quantum mechanics state that this state space is in fact complete, making it a Hilbert space, and it can be seen that the element $a^\ast = \langle a,\,\cdot\,\rangle$ is continuous. Now denote by $\mathcal H^\ast$ the topological dual of $\mathcal H$, consisting only of continuous linear functionals. The Riesz representation theorem asserts that $a\mapsto a^\ast$ is an isometric isomorphism between $\mathcal H$ and $\mathcal H^\ast$. You should see the latter as the space of bras, and so we see that indeed every bra vector is the conjugate of a ket vector. Starting from that point, in physics one forgets about the distinction between $\langle a,b\rangle$ and $a^\ast(b)$, which are both denoted $\langle a|b\rangle$. It is even customary for this reason to write $\langle a|$ for $a^\ast$ and $|b\rangle$ for $b$.
ADDED IN EDIT
As commented by ACuriousMind, it can be enlightening to make this concrete for the finite dimensional case. In the finite dimensional case, if we fix a basis, $a$ and $b$ can be written as
$$a = \begin{pmatrix}a_1\\ \vdots \\ a_n\end{pmatrix},\ \ \ b = \begin{pmatrix}b_1\\ \vdots \\ b_n\end{pmatrix}.$$
The inner product is $\langle a,b\rangle = a_1^\ast b_1 + \cdots + a_n^\ast b_n$, where $a_i^\ast$ is the complex conjugate of $a_i$. The linear functional $a^\ast$ is represented by a matrix in this basis, namely
$$a^\ast = \left(a_1^\ast\ \cdots\ a_n^\ast\right).$$
Clearly we have $a^\ast(b) \equiv a^\ast b = \langle a,b\rangle$.
ADDED IN SECOND EDIT
The above argument is a strictly mathematical one, in which the (common) assumption is made that kets are the elements of some Hilbert space and bra's are defined to be elements of its continuous dual. This definition is mathematically convenient but not physicaly unavoidable.
First of all, only kets directly relate to physical reality, bra's are just there for mathematical convience. The convenience, and the whole usefulness of the Dirac formalism disappears when you abandon the duality between bra's and kets.
ZeroTheHero remarked that in the book of Cohen-Tannoudji e.a. the definition of bra's and kets (for a single spinless particle) are such that this duality doesn't strictly hold. The authors do acknowledge the computational desirability of this duality, and propose a formal solution, in which the duality is supposedly restored, but with the understanding that not all elements are physical (only aproximately so), and without going into details. I do think they take great care to indicate possible pain points in the formalism, and probably they do the right thing by not going into distracting detail.
My guess is that their intention was to give a pragmatic approach in which physical motivation and intuition are preferred over mathematical rigor. To be specific, first of all they define the Hilbert space of kets $\mathscr F$ to be a subspace of $L^2$ of "sufficiently regular functions" of which they "shall not try to give a precise, general list of [...] supplementary conditions".
Then they define the space of bra's as the space of all linear functionals on $\mathscr F$, the space that in my earlier notation would have been $\mathscr F^\vee$. I don't think it is ever useful to consider the entire (algebraic) dual in the infinite-dimensional case, since this space is huge, and full of highly pathological elements. They'd better have "defined" it as an otherwise unspecified subspace of "sufficiently regular" linear functionals.
Then they construct a very reasonable bra (namely evaluation at a point), and show that it is not associated to any ket, and finally they note that this can be physically resolved by going to generalized kets to restore the duality, even though one should not attribute a physical meaning to them. Many reasonable bra's correspond to a generalized ket, but this is still not the case for the large majority of the elements of $\mathscr F^\vee$.
Comment: Since OP is talking about complex conjugation, you could mention that in finitely many dimensions, or if we take $L^2(\mathbb{C})$, this dual indeed is closely related to complex conjugation.
Comment: @ZeroTheHero I am saying that if we assume the state space to be a complex Hilbert space, a common assumption made in QM, then the space of bras and the space of kets, where bras are taken as elements of the continuous dual, are isomorphic. This is a mathematical theorem, hence non-negotiable.
Comment: @ZeroTheHero (continued) In the book you are referring to, the set of bra's is defined as the vector space of *all* linear functionals on $\mathcal H$, a space that I referred to as $\mathcal H^\vee$. This space is incredibly much larger than $\mathcal H^\ast$, mostly full of meaningless elements, but indeed some elements, like the one constructed by Cohen-Tannoudji, are not all that pathological.
Comment: @ACuriousMind Thanks, done! (if this is what you had in mind)
Comment: According to the seminal book on QM by Claude Cohen-Tannoudji *et al*, there are bras to which correspond no kets.  See Chap.2, section B.2.c.$\delta$.
Comment: @ZeroTheHero What *is* negotiable of course is whether we should really insist that the state space is a Hilbert space, or if bra's should be restricted to being continuous.
Comment: Let me rephrase...possibly you could sharpen your answer to highlight this point?
Comment: @ZeroTheHero Done. It got a bit long, sorry!
Comment: @doetoe thanks.  Can you clarify the "this" in " I don't think this is ever useful": presumably you mean defining the space of bras as the space of *all* linear functionals?  (I upvoted your answer.  Given the prevalence of the Cohen-Tannoudji book it is excellent to clarify this part of it.)
Comment: @ZeroTheHero yes indeed, edited to make it clearer
Comment: Actually correct frame would be rigged Hilbert spaces. So you take a dense subset of H and then for the continous dual of that said space, this is larger than the hilbert space, and also includes the generalized eigenfunctions of position and momentum space
Answer: You can take inner product of any 2 vectors if they have same dimension. However, we consider the physics problem in quantum mechanics, where inner product of bra and ket vector (of course is complex conjugate of bra vector) of wave function means probability density of finding particle. Inner product of 2 arbitrary vectors (with same dimension) is no meaning in quantum mechanics.
Comment: Of course the inner product of two arbitrary vectors has meaning. If $|a>$ is some arbitrary ket state, and $|b>$ is an eigenvector of some Hermitian operator (every vector is an eigenvector of SOME Hermitian operator!) then $$ is the squared probability of measuring $|b>$ when applying the Hermitian operator. That's a pretty important meaning!


How to compute flow direction and flow accumulation with Qgis?

Question: Any one who had made flow direction and flow accumulation on raster data for filled evaluation model i Qgis? Which tool and plugins are necessary, i haven't been able to find any guidelines on Google
Answer: 4 years later - if anyone stumbles across this while using QGIS 3.4, I found the simplest/most-robust solution was simply use the GRASS r.flow tool. The only real input is your DEM, and it outputs flow accumulation and associated data layers without having to do multiple steps. (for the gui:  processing --> toolbox --> GRASS --> Raster --> r.flow).
Make sure you are using a CRS that uses meters, not lat/long. You may need to reproject your DEM.
From there you can recategorize the flow accumulation to retain only zeroes, if you are looking for ridgelines, predict stream locations, etc. Both results (stream and ridge) matched pretty well our empirical data, using a NASA ASTGTM2 DEM.
Answer: FYI, in [2.0.1 Dufour] Sextante is now core functionality - no need to install the plugin.  Just go to the 'processing' menu and it's there!
...took me 3 days to work out why I couldn't install it as a plug-in ;-)
Answer: Your best bet is probably to use the SEXTANTE plugin.
Go: SEXTANTE->Geoalgorithms->Domain Specific->Hydrology
Here you will find a number of tools roughly analogous with some of the hydrology tools in ArcGIS.  This link on Hydrological Analysis and this one on Hydrology analysis with TauDEM from the Sextante Cookbook may prove useful.
EDIT
I forgot to mention 'Fill Sinks' which is in a different part of SEXTANTE.  It comes in 3 'flavours' and the 'Fill Sinks (Wang & Lui)' version will also output flow direction and watershed basins.
Go: SEXTANTE->Geoalgorithms->Domain Specific->Terrain Analysis and Geomorphology->Fill Sinks.
Comment: You can also enable GRASS GIS in SEXTANTE which gives you even more options: http://grasswiki.osgeo.org/wiki/Hydrological_Sciences
Answer: I have been able to obtain flow direction & flow accumulation but not with QGIS processing toolbox. I used Grass pluggin - and then since I loaded OSGeo4W - I repeated in GRASS 6.4.4.
Process - establish NewMapset - use Open Grass Tools - make sure DEM is in .asc format - that is the best image type that I got to work(I opened QGIS - Raster - conversion- translate) - r.fill.dir - (other formats never finished running this fill step) - r.watershed (this will give you flow direction & flow accumulation...I was told you could use the GRASS conmmands in the QGIS processing toolbox - however I was not able to get them to 'work' they produced outputs - but the output files did not match any other software outputs I had tested (ArcGIS - was one)....
See the image - the one on the left is from GRASS pluggin & the one on the right is from QGIS processing toolbar - to obtain stream order- I was not able to get a good/comparable output from the Processing Toolbox....  I am new and figuring this out - so watch you CELL SIZE - after editing my cell (SET REGION in GRASS) to the correct 30 m (.0027777778) cell size - this process takes a long time on my 1GIG sample area
Comment: I have also used SAGA GIS for flow accumulation, which can be installed with the OSGeo4W installer and is then available in the Processing toolbox.


'op_invalid_limit' error trying to send asset

Question: I'm trying to send an asset on testnet and I'm getting this error: op_invalid_limit. What could this mean?
Comment: StackExchange blocks too short questions intentionally. You haven't provided any source code, only a vague error description. In most cases it's not enough to troubleshoot the problem.
Comment: yes, of course that's why it was done. I've intentionally not provided any source code as I'm using an SDK built on top of Stellar's SDK - it would not be helpful to anyone. I was *hoping* this issue could be gleaned from the error code, which - as you've correctly pointed out - is rather vague. thanks for the edit and the answer, I'll dig on.
Answer: You can find all possible errors for operations in List of Operations doc.
CHANGE_TRUST_INVALID_LIMIT  -3  This operation would drop the limit of this trustline below the amount of the asset the account currently holds.

Answer: It looks like you are trying to invoke the Change Trust operation while providing the wrong limit (maybe 0). Check your source code.


Organized sources of information collected by Cassini-Huygens?

Question: I'm looking for places or repositories where is the information collected by the Cassini mission including the Huygens probe at Titan, ideally curated or organized in some way.
Comment: What level of "information" are you looking for? Popular press articles? Scientific review (more general overview) articles? Papers in scientific journals? The actual data from the science instruments?
Answer: For a start read the Wikipedia article. The next step would be the more than 100 references at the bottom. Many links to NASA, JPL and ESA documents.
Comment: There are probably much better answers to this question than  the random assortment of links at the bottom of a Wikipedia article.
Comment: I spect nasa PDF's , i yet read wikipedia
Answer: The Cassini-Huygens mission was a fantastically successful flagship-class mission to the Saturn system, with the Cassini spacecraft spending 13 years in orbit there and delivering the Huygens probe that made the first successful hard-surface landing in the outer solar system. The results are so voluminous, and cover so many different aspects of the Saturn system and so many scientific disciplines, that even a brief overview of the most intriguing results would be far more than any popular press article could accept.
There are online sites hosted by NASA and ESA with information about Cassini and Huygens, but I found the NASA highest-level Cassini site lacking, with no useful links to pages with more detailed information. The ESA site is better in this respect than the NASA site, even for Cassini, and contains those links the NASA site lacks — to NASA pages!
For a high-level overview of science results, the post-mission review paper by Linda Spilker (unfortunately behind a paywall, if you're not an AAAS member) covers the principal science results, at least those that would fit within the Science journal's page limits. It includes copious references to the initial science papers reporting those results. But since the Cassini-Huygens data set (some 3 Tbits of raw downlinked data in the prime mission alone) has produced more than 4,000 science papers (!) there is no single publication or web site that covers, even summarizes, it all.
If you want the data themselves — and this is not for the faint of heart! — they're all publicly available from the Planetary Data Set, "PDS",. For Cassini the PDS organizes data by discipline, into nodes: there's an "Atmospheres" node, an "Imaging" node, a "Ring-Moon Systems" node, etc. The Atmospheres node also serves as the repository for general information about the mission that aids in accessing, reducing, or interpreting the data. That site also has many useful links to other information sources. This Planetary Society site tells how to access and use imaging data, and has some general information about the PDS, with many links, including links to an alternate data repository, the National Space Science Data Center, "NSSDC".
For Huygens data, ESA maintains a data repository at their Planetary Science Archive, "PSA". The Planetary Society site offers a link to this ESA site.


I'm planning to become a very successful man and prove the world who I am and what I am capable of, but is it haram?

Question: I am a student who has a very bad past(porn addiction, mental illness and a very bad person to my society) and now I want to prove the world what I am capable of by becoming successful. my question is, if I want to become successful and show my friends and family what I am capable of then am I seeking fame and if I am seeking fame is it haram?
Comment: How often will you spam the site with similar questions? Please delete one of your posts and wait maybe you'll get an answer. If anybody commented your question you should act upon a comment asking for clarification. We further expect a prior research effort to be shown which is missing in your post. (see [ask]).
Answer: Bro you can see these scholares
https://images.app.goo.gl/ToyFh2ASHRwhwazk6
You can say that these are islamic scholars promoting deen but they to have fame.
And no were in quran or hadeed it is written "not to get fame".
So you can have fame.


What do the "coefficients" in R's HoltWinters function represent?

Question: I'm using the HoltWinters function in R and I'm trying to understand what the "coefficients" represent in the object that is returned by that function.  They don't seem to match in any obvious way the values returned when you look at the $
Comment: Did you leave off something on the end of your question?
Answer: +1 this is confusing. If your time series has length $N$ and frequency $p$, then the so-called "coefficients" (which can be accessed as HW$coeff if HW is the object returned by HoltWinters) are exactly the values $a[N]$, $b[N]$ and $s[N-p+1]$, $s[N-p+2], \cdots s[N]$ where these are defined by the formulas in the Holt Winters help page, which can be accessed from within R with ?HoltWinters.
For the additive model, which is the default, suppose my.ts is a time series object with positive frequency $p$. The values of $a[N-1]$, $b[N-1]$ and all the earlier $s[t]$ up to $s[N-p]$ are given in the table HoltWinters(my.ts)$fitted. The values in HoltWinters(my.ts)$coeff are calculated from these using the formulas
$$a[t] = α (Y[t] - s[t-p]) + (1-α) (a[t-1] + b[t-1])$$
$$b[t] = β (a[t] - a[t-1]) + (1-β) b[t-1]$$
with $t=N$ and $\alpha = $ HoltWinters(my.ts)$alpha, $\beta = $ HoltWinters(my.ts)$beta, and
$$s[t] = γ (Y[t] - a[t]) + (1-γ) s[t-p]$$
with $t=N-p+1, \ldots, N$ and $\alpha = $ HoltWinters(my.ts)$alpha, $\beta = $ HoltWinters(my.ts)$beta, and $\gamma = $ HoltWinters(my.ts)$gamma.
This works for $a$ and $b$ (the level and trend) but when I do the calculation for the seasonals, I get slightly different values (within 5% or so) than are given in the output. I hope somebody can edit this answer to explain what is going on with the seasonals. Here is a link to the C code for the hw function which is called by the HoltWinters function:
https://svn.r-project.org/R/trunk/src/library/stats/src/HoltWinters.c
Answer: The meaning of the a, b, s, alpha, beta and gamma parameters is described in the help on the HoltWinters function (try ?HoltWinters in R), under Details.
e.g. the additive model is described so:
Yhat[t+h] = a[t] + h * b[t] + s[t - p + 1 + (h - 1) mod p],
where a[t], b[t] and s[t] are given by
a[t] = α (Y[t] - s[t-p]) + (1-α) (a[t-1] + b[t-1])
b[t] = β (a[t] - a[t-1]) + (1-β) b[t-1]
s[t] = γ (Y[t] - a[t]) + (1-γ) s[t-p]

If we look at the help, one of the examples is:
(m <- HoltWinters(co2))
plot(m)
plot(fitted(m))

With output:
Holt-Winters exponential smoothing with trend and additive seasonal component.

Call:
 HoltWinters(x = co2)

Smoothing parameters:
 alpha:  0.5126484
 beta :  0.009497669
 gamma:  0.4728868

Coefficients:
           [,1]
a   364.7616237
b     0.1247438
s1    0.2215275
s2    0.9552801
s3    1.5984744
s4    2.8758029
s5    3.2820088
s6    2.4406990
s7    0.8969433
s8   -1.3796428
s9   -3.4112376
s10  -3.2570163
s11  -1.9134850
s12  -0.5844250

Now let's look at the output of calling coefficients:
coefficients(m)
          a           b          s1          s2          s3          s4
364.7616237   0.1247438   0.2215275   0.9552801   1.5984744   2.8758029
         s5          s6          s7          s8          s9         s10
  3.2820088   2.4406990   0.8969433  -1.3796428  -3.4112376  -3.2570163
        s11         s12
 -1.9134850  -0.5844250

Which correspond exactly to the output of the same quantities generated before.
Taking into account the description of a, b, s, alpha, beta and gamma on the help page, which parts are unclear to you?
Comment: Could you tell which time point are "a" and "b" representing?
Answer: I agree that there is puzzle. To see the puzzle I considered
the co2 series available in R. The answer is long. May you just to the *-part that I added today
I have expected that
co2HWBis$coefficients[2]

equals
co2HW$fitted[length(co2HW$fitted[,3]),3]

i.e. the coeff equals the last extimated trend.
Below you can check that this is not the case.
However
co2HW$fitted[length(co2HW$fitted[,3]),3]

equals coefficient you were to obtain if you drop the last value
of the series as is deomestrated below. I suspect that the coefficient is
somehow "written forward". I find it furthermore puzzling the matters are
different if you allow beta to be estimated.
I reading the source code
(http://svn.r-project.org/R/trunk/src/library/stats/R/HoltWinters.R)
but I am not yet sure what goes on.
This is the complete code
    rm(list=ls())

    co2HW = HoltWinters(co2, alpha = 0.2, gamma = 0.2, beta = 0.5)
    # co2HW$coeff[2]
        co2HW$fitted[length(co2HW$fitted[,3]),3]

    co2Bis = window(co2,end=c(1997,11))
    co2HWBis = HoltWinters(co2Bis, alpha=0.2, gamma=0.2, beta=0.5)
    co2HWBis$coefficients[2]
        # co2HWBis$fitted[length(co2HWBis$fitted[,3])-1,3]

    co2HW$beta*(co2HW$fitted[length(co2HW$fitted[,2]),2] -
        co2HW$fitted[length(co2HW$fitted[,2])-1,2]) +
        (1 - co2HW$beta)*co2HW$fitted[length(co2HW$fitted[,3])-1,3]

    #####################

    co2HW = HoltWinters(co2, alpha = 0.2, gamma = 0.2)
    # co2HW$coeff[2]
        co2HW$fitted[length(co2HW$fitted[,3]),3]

    co2Bis = window(co2,end=c(1997,11))
    co2HWBis = HoltWinters(co2Bis, alpha=0.2, gamma=0.2)
    co2HWBis$coefficients[2]
        # co2HWBis$fitted[length(co2HWBis$fitted[,3])-1,3]

    co2HW$beta*(co2HW$fitted[length(co2HW$fitted[,2]),2] -
        co2HW$fitted[length(co2HW$fitted[,2])-1,2]) +
        (1 - co2HW$beta)*co2HW$fitted[length(co2HW$fitted[,3])-1,3]

*-part
... one night later I think I can give an answer that looks like an answer. In my opinion the problem is the timing of the table co2HW$fitted. The last line is not the estimated trend level and saison of the last period in the sample. The coefficients are the estimated level, trend and saison of the last period but these value are not displayed in the table. I hope th following code is convincing
rm(list=ls())
x = co2
m = HoltWinters(x)
# m$fitted[length(m$fitted[,3]),3]

aux1 = m$alpha*( x[length(x)] - m$fitted[length(m$fitted[,3]),4]  ) +
    ( 1 - m$alpha )*( m$fitted[length(m$fitted[,3]),3] +
m$fitted[length(m$fitted[,3]),2] );
aux1
m$coeff[1]

aux2 = m$beta*(aux1 - m$fitted[length(m$fitted[,3]),2] ) +
     (1-m$beta)*m$fitted[length(m$fitted[,3]),3]
aux2
m$coeff[2]

m$coeff[14]
    aux3 = m$gamma*(x[length(x)] - aux1) +
( 1 - m$gamma )*m$fitted[length(m$fitted[,3]),4]
aux3

Comment: Welcome to the site, are you the original poster of the question? This doesn't appear to be an answer.
Comment: Thanks @user28623! I agree that there is something fishy about it. I also tried to read the source code but didn't make progress.
Comment: I posted the co2 stuff and I think I figured out what is going on. First, the last value of `co2HW$fitted[,3]` is not the estimated trend of the last period of the sample. It is the estimated trend of one period before that last period. Second, `co2HW$coeff[2]` is the trend of the last period. In my opinion the timing of the table of `co2HW$fitted` is misleading.
Comment: @user28623, do you mean `co2HW$fitted[,1]` instead of `co2HW$fitted[,3]`? and `co2HW$fitted[,1]` is supposed to be `level`, not `trend`. i think your answer is really helpful, but a bit confusing
Answer: I think the key point about the coefficients, which I couldn't see in the other answers but may have missed, is that they are the values of smoothed level and  smoothed trend for the last period in the time series on which the forecast was based/made;  and smoothed seasonal components for the last 12 months of that time series.
Understanding the table of fitted values for the forecast also helps. For each row corresponding to time t, the values of level and trend are the smoothed values for time t-1, and the value of season is the smoothed value for t-p. These are added to give the estimated true level for time t, Xhat.
I have only begun to use R fairly recently, so apologies if my terminology isn't fully accurate.
Comment: I don't think the question is clearly stated . As glen_b points out it is incomplete. Since the question is unclear I don't see how an answer can be given.
Answer: This is from the HoltWinters documentation in R. I had the same question and this answers why I could not calculate the same seasonal values. The function is using a decomposition method to find all the initial values when incorporating seasonality, whereas for single and double exponential smoothing it doesn't do this.
"For seasonal models, start values for a, b and s are inferred by performing a simple decomposition in trend and seasonal component using moving averages (see function decompose) on the start.periods first periods (a simple linear regression on the trend component is used for starting level and trend). For level/trend-models (no seasonal component), start values for a and b are x[2] and x[2] - x[1], respectively. For level-only models (ordinary exponential smoothing), the start value for a is x[1]."
Found this website that explains how to get initial values: https://robjhyndman.com/hyndsight/hw-initialization/
Answer: Coefficients in Holtwinter's  Method
In the HoltWinter's model with seasonal= 'additive', I am able to produce the model output for coefficients manually. It seems like we need to use a[N-p],b[N-p] instead of a[N-1],b[N-1] in the HW formula. This may be because 'a' and 'b' depend on 's' component. I think the coefficients are the smoothed out values for the Nth data and for the last season. If the season has length p, then there will be p many smoothed values.
result=HoltWinters(co2,alpha=NULL,beta=NULL,gamma=NULL,seasonal = 'additive')
result$coef
let us produce the coefficients manually
alphat=0.5126484
betat = 0.009497669
gammat=0.4728868
N=length(co2)
p=length(result\$coef)-2
A_N=alphat*(co2[N]-result\$fitted[N-p,4] )+(1-alphat)*(result\$fitted[N-p,2]+
result\$fitted[N-p,3])
A_N
B_N=betat*(A_N-result\$fitted[N-p,2])+(1-betat)*(result\$fitted[N-p,3])
B_N
S_N=gammat*(co2[N]-A_N)+(1-gammat)*result\$fitted[N-p,4]
S_N


How to tighten a wooden bannister (newel post)

Question: How to tighten a wobbly stair bannister?  I tried going in from the basement ceiling, the floor boards are in the way.  I tried drilling in a screw at an angle at the base to anchor to the bottom stair, and lets just say I now need to figure out how to extract a broken screw and patch a hole to lessen the carnage.  I imagined there is a nut/screw job under the wood that needs to be tightened, but darned if I can figure out how to get to it without ripping up the wood. I could try some glue, I suppose, there is a tiny gap around the bottom, but that doesn't seem like it would last past a few pulls.
Comment: What, exactly, is loose? The newel post? Photos (above and below) would be very helpful.
Answer: I guess you already know that your attempted fix is a fail. One realistic way that such a newel post can be made more sturdy would be to do some re-work to the structure as follows:
A flat metal bracket is made with a round metal post welded to it. The round post (0.75 to 1.0 inches diameter recommended) would extend up through a round hole in the lower stair tread and rise up to a height of 10 -> 12 inches. The metal base plate is screwed up to the bottom side of the stair tread. The center core of the newel post would then be bored out to permit the newel post to be mounted on the projecting round post. (See picture below).
Answer: This is a tough repair to do without taking your entire balustrade apart.
Try to remove the bullnose riser. This might give you an opportunity to tighten up the newel post from below. (Long screws, glue, whatever you can think of...)
If this doesn't work, something like a Zipbolt (eg ZB 10800 UT MINI) might do the job, though this would entail pulling (possibly cutting) the bottom of the newel post away from the tread in order to drill the newel and tread.
Good luck!
Comment: Well it's your house but I believe it is worth while cutting an opening in the floor boards, as long as you can keep it entirely inside the stairs, and you can add headers to brace up any sub floor boards you have to cut.
Answer: This is likely a factory made bullnose riser, because it is round. It will have a bottom and a top firmly glued into the round part of the riser assembly. The idea is to install a 1" dowell up into the newel and down through the tread, the riser top, the riser bottom, and even on through the floor.
Your installer skipped that step. And there's a broken screw that has forced a space between tread and newel. IMO there is no way to fix this.
Consider buying a new newel. Buy one with a square base. Paint in contrasting color since you cant match the stain. Remove the tread. Next  make absolutely sure the carriages and riser assembly are bombproof strong. Everything else you will do depends on it. Install blocking between the carriages. Then build up the inside of the riser assembly solid with layers of wood, screw and glue layers, attach the risers very well to the blocking. Then glue and screw the tread back down on your bombproof carriages and riser. Once again, bombproof. All the strength will depend on it not moving. With your new newel buy a newell mounting kit. It is 1/4 inch plate steel about 4 3/4 x 4 3/4 with holes drilled in it and 4 pieces of special trim to cover. Screw the plate to your newel. You will notice the plate sticks out about a half inch all the way around the newel and has exposed holes. Screw the newel to the tread. Cover the plate with the special trim.
I always prefer the oak dwell connection, but it is not always possible. When forced to use another method, I have had good luck with these mounting kits.


need a good reference for introduction to elementary theory of groups

Question: I've recently become interested in the elementary theory of groups due to Sela and Myasnikov-Kharlampovich's work with free groups.  I'd like a good introduction to the field of the elementary theory of groups, and in particular I'd like a reference to contain examples of group properties that cannot be read from a group's elementary theory.  For example, it seems that the statements "G is vritually abelian" or "G is hopfian" could not be expressed with first-order sentences, but I don't have enough knowledge yet to determine if such things are true.  Does anyone know such a reference?  Or, specifically, does someone know a proof of the fact that being hopfian (or some other group property) can't be read from a group's elementary theory?  Thanks!
Answer: I learned a lot from reading Bestvina and Feighn's article Notes on Sela's work: Limit groups and Makanin-Razborov diagrams.  It's not a broad introduction to elementary theory, but it does express some of Sela's ideas quite succinctly.  You may need a background in geometric group theory (specifically, in understanding laminations on 2-complexes or group actions on $\mathbb{R}$-trees) to get the most out of it.
Regarding the question of whether or not the Hopf property is elementary: the answer is obviously `no' if you allow infinitely generated examples.  Indeed, consider the free group on countably many generators, $F_\infty$.  The elementary theory is completely determined by the set of finitely generated subgroups, so $F_\infty$ is elementary equivalent to $F_2$.  But $F_2$ is Hopfian and $F_\infty$ is not.
EDIT: I'm getting a little nervous about the claim that the elementary theory is determined by the list of finitely generated subgroups.  However, Sela and Kharlampovich--Miasnikov proved that the natural inclusions $F_n\subseteq F_{n+1}$ are elementary embeddings, from which it does indeed follow that $F_\infty$ is elementarily equivalent to $F_2$.
I don't know a finitely generated example, although I agree that one must surely exist.
Comment: Henry is too bashful to point it out, but he wrote a very nice set of solutions to the exercises in Bestvina-Feighn's paper (some of which are pretty hard, so they make BF's paper much easier to read).  They are located here : http://arxiv.org/abs/math.GR/0604137
Comment: dan, people have certainly thought about these things.  My impression is that to construct *finitely generated* counterexamples to show that a certain property isn't elementarily is just, in general, a very difficult problem.  Logicians seem to like to construct elementarily equivalent groups via ultrapowers, which of course give infinitely generated examples in general.  From a logical point of view, finitely generated examples aren't particularly natural, since being finitely generated is not an elementary property!
Comment: I second @Andy's comment.
Comment: Thanks for the reference Henry.  To get a general introduction to the elementary theory of groups I have looked at some Model Theory books, but these books rarely reference groups directly.  Is it possible that people haven't thought that much about what group properties can be read from the elementary theory of a group?
Answer: You might try Champetier and Guirardel's Limit groups as limits of free groups.
It has a short section (section 5) on elementary and universal theory, though perhaps none of the "non-examples" you're looking for.  It is, however, a pleasure to read and if you're interested in limit groups, Makanin-Razborov digrams, etc. I highly recommend it.
Comment: Thanks for the reference Jeremy.  That paper is what got me interested in the elementary theory stuff, but their introduction to the theory is very brief.


How can I open two documents at once in Google Drive?

Question: I wonder how I can open two documents at once in Google Drive. Selecting two documents then hitting on ENTER didn't do the trick (no document gets open)
Answer: Quick answer: More browser tabs.
In general, it depends. It hinges on distinctions that are subtle to some people (the UI makes them look similar). To be honest, it's a usability design problem that all this is so subtle and complicated.

When using Google Drive in the browser, if you select one of its built-in file types (Google Docs, Sheets, Slides, ...) then press Enter, it will open the web-based editor in a new browser tab. This also works with apps like MindMup that install into Google Drive.

To open another such document at the same time, just switch back to the Google Drive tab, select another document, and press Enter or double-click it.

When using Google Drive in the browser, if you select a PDF, photo, plain text file, audio file, Word doc, etc. then press Enter, it will open a read-only preview of that file overlaying the Google Drive file list in the same browser tab.

To open another such preview, just open another browser tab, navigate to the Google Drive folder, select your file, and press Enter.

When using Google Drive in the browser, if you select a document type that it doesn't handle, the only thing Drive can do with it is download it to the local disk on your computer or Chromebook. Also you can choose to download a PDF or similar file that Drive can preview.

After downloading a file, you can open it in any suitable program you have available. For a PDF, that could be Adobe Reader, Apple's Preview program, the quick-look feature within the Macintosh Finder, or others. These will each offer different features.
To open multiple such files, just download them all, then open them into separate windows/applications.
Caution: After downloading a PDF file in Chrome, clicking the "downloaded file" button at the button of the window will open the PDF file in a new browser tab, even though you took pains to download the file. You probably downloaded a PDF to open it in Apple Preview or Adobe Reader, and that's not what happened. To fix this, close the browser tab, switch from the browser to the desktop, then open the downloaded file there.

When using Google Drive synchronized to a folder on your computer's desktop, you can open multiple files into separate windows/applications. Here you're using your local desktop software to open the files and optionally to choose the apps.
(Yet more cases!) When you're in the browser and see a link to a PDF file (this might also work for a recorded audio file), clicking, or Command-clicking, or Control-clicking, or right-clicking the link might (A) open the file in the browser tab, (B) open it in a new browser tab, (C) download it to your local disk. The right-click menu gives you better control over these alternatives.

It does matter whether you open a PDF file in Chrome vs. Preview vs. Reader if (for instance) you want to copy some of its contents or fill in a form.
Comment: This answer is about how to deal with a missing feature, right?
Comment: @Rubén I think of it as dealing with a usability problem rather than a missing feature. The UI is too complicated, partly because it tries to do us a favor, or rather, different favors in different cases.
Comment: BTW it's also fine to open Gmail in two or more tabs. Very handy. The only hitch is that you have to reload a tab to get any edits to Contacts.
Answer: I don't know about 2 files, but Alice Keeler has a Chrome extension that allows you to open the first 20 files all at once:
Drive 20


How to restrict access to unwanted sites?

Question: I use Ubuntu 13.10. I tried to used OpenDNS to restrict some websites. Unfortunately, I couldn't do that. I use AirStream 1200 USB modem to access WiMax internet. OpenDNS setting didn't work for me at all. Any alternatives to OpenDNS or any methods to secure my web browsing. I want solution that can't be easily hacked.
Comment: OpenDNS is a reasonable choice to achieve your objective of secure web access. Perhaps should you add details about your setting problems with OpenDNS.
Comment: @danielAzuelos Whenever I add domain of OpenDNS in IPv4 setting, I am unable to access internet. So, I can't use that setting.
Comment: I advise you to start another question about your need for `OpenDNS` trouble shooting, because you are on a right path.
Comment: @danielAzuelos I don't think, I need openDNS now. Your suggestion worked for me.
Answer: I advise you to install squid.
It is a highly customisable web cache providing many configuration possibilities to protect of most of the attack web servers.
I'm using it to protect my network of add web servers, spying web servers,
any web servers without a DNS name, and many other sorts of attacks.
I'm testing many a priori filtering, and most of them are successfull:
when checking afterward the blocked web server I often discover a well
of malware.
Comment: My comment is that if @Habi hasn't been able to configure the client to properly use OpenDNS, it will (probably) be even harder for him to configure Squid properly! :)
Comment: I'm afraid you are right :). But for the OQ (and other readers) `squid` seems better suited than `OpenDNS`, under total contral for who wants to learn.
Comment: @scuzzy-delta After configuring my computer as per instruction provided in OpenDNS site, I was unable to connect to internet and evenmore, I tried to apply second option(i.e. configuring router). But, alas, I'm using modem to connect to internet.
Answer: A simple way would be to add the site to the /etc/hosts file but instead of adding its IP address you use any other IP. For example 127.0.0.1. This will always resolve the site name to this IP address. I hope I did understand your question.
Comment: This method won't scale well with the number of bad web servers. Moreover, some dirty web servers will use URL with an explicit IP address.


Does a neutral wire need to be run from a switch to the light?

Question: We have an older church building that we would like to put our parking lot lights on a timer. We purchased digital timers only to find out that there is not a neutral wire within the switch boxes. We would like to run a neutral wire from the breaker box to the switches, does the neutral wire have to continue out to the lights? The switches only have 2 wires into and out of them, no ground.
Comment: Can you post photos of the insides of the switch boxes in question please?
Comment: That's *really unusual* unless the light switches are out in the parking lot. Where are the switches?  Are you sure you're telling us about every single wire in the box, including ones that do not go to the switch?  Getting us photos as ThreePhaseEel advises would be VERY helpful, [edit] your answer to include them.  If you take your pix from a different device than you posted the question from, then register your account to an email/password or Google/Facebook ID so you can log back in from any device.
Comment: Without knowing the scale of the parking lot lighting, I wonder if the switches are controlling relays that control the light circuits. Other than that, seems like a normal switch loop setup, rather than "really unusual" - but rather than running from "power at the overhead light" to the switch location, running from a junction box on the way from the electric panel to the parking lot, branching the switch loop off to the switch location.
Answer: A church is a commercial facility so use caution on advice received on this site most are not familiar with the unique requirements to commercial construction. Could you provide a photo of the wires entering the box?
Also how many lights and the type?
there may be a contactor controlling multiple runs I use 3 phase contactors to control 3ea 20 amp strings on 120/240v services.
there are timers that need no neutral check out an intermatic STO1 they run in the mid 30$ range and the timer is battery powered so no neutral is needed and power bumps don't affect it. The battery last about 2 years.
The nice thing about this timer is it is astrometric or you can turn on a feature to turn on at sunset and off at sun rise it updates itself based on your location. I use them at my plant to turn the yard lights on at 3am then off at sunset, on again at sun set then off at 1030 pm or the time they shut down for that day then they don't turn on for a day that we never work would be great for a church where scheduled services and weekly Bible studies or choir practices. If you need it on when it's not programmed tap it and it will stay on until tapped again or the next scheduled off time. I drive small (15 & 20 amp circuits) with this timer and if the loads are larger drive contactors (power relays).
Depending on the area and construction type you may have conduit that's why I asked for a photo and a neutral could be pulled in conduit in commercial facilities. buildings with occupancy requirements are normally wired with conduit.
Answer: Retrofitting a cable with a neutral wire may be far more expensive than a different solution that does not require rewiring the building - unless by chance you have conduit for the wiring? If you do have conduit, it's a simple retrofit and you'd only need to get the neutral to the switch location - the lights already connect to neutral somewhere else. The neutral to the switch location would need to be the same neutral that the lights are using. That neutral should be present where the switch loop branches off from the light circuit. And it has to be a whole new cable with neutral if it is a cable rather than conduit setup.
NEW installations are required to provide neutrals (and grounds) at switch locations.
Different options would include putting the timers in a different location in the circuit where neutral is already available. While not as convenient as having the switches and timers at the same location, you might not need to use the switches so much (or at all?) with the timers in play.
Comment: Kinda depends how old the wiring in the church is; I'm hopeful that it's conduit because it is an occupancy that should be (and it makes the fix easy), but most of the churches I know were electrified a LONG time in the past, as they were around for a good while before electricity came out. How much they got updated after that tends to be limited, as there's always something else (like the roof) that needs funds.
Comment: Wiring in a commercial facility usually requires conduit. Thinking NMB ? It's only appropriate for residential 1-2 family (class 3,4,5 ).
Answer: You can't run a neutral from the panel to the switch;  code requires that the conductors of the circuit all must run together.  So if you're going to run a neutral, you'll want to run it from the light to the switch.
Some electronic switches, like timers, operate without a neutral, using the safety ground for the return current for the electronic controls.  If there's a safety ground present, that's probably the easiest solution.  Note that this only works if the device is specifically designed to operate that way - it's not OK to substitute the safety ground where the instructions tell you to use a neutral.
So if there's a green ground wire present, that's probably the easiest solution.  If the wiring is run in conduit, the conduit can serve as the safety ground;  but if there's conduit, you could just run a neutral wire to the light in the conduit.
It is probably possible to install the timer (or a photocell) in a location upstream from the lights.  The switch could still be used to override the timer to turn the lights off.
There are also smart switches / wireless automation products that would allow you to install the control in that upstream location and program the lights for a schedule.

Note that a church is what the National Electrical Code considers an "Assembly Occupancy" and there are a few special rules that apply - see NEC article 518.  In particular, it adds restrictions on the wiring methods permitted.  Depending on the fire rating requirements of the building, NM cable (Romex) might not be permitted.
Comment: @Ed Beal - A lot of churches around here are old, not always GEC, BX cable, a lot are wiremold - some were gas lit when built and had electric lights added later (later being 1920's haha)  But you see a little bit of everything in churches, volunteer work, etc.
Comment: Wiring in a commercial facility usually requires conduit. Thinking NMB ? It's only appropriate for residential 1-2 family (class 3,4,5 ).


What are the most significant contributions Slavoj Žižek has made to the field of philosophy?

Question: What are the most significant contributions Slavoj Žižek has made to the field of philosophy, perhaps in particular to political philosophy?
Comment: I think he's more of an agent provacateur who makes the field interesting, entertaining. He's a kind of a publicist for a certain kind of intellectual endeavour.
Answer: Although Hegel was always important, especially due to Marx, he seems to have given a freshly challenging Hegel to the world. Also, surely, the Slovenian School, has all but appropriated the body of Lacan, and distorted the previous reading to the point of an alienation, that is now applied by practicing analysts.
If you know how to do a search of the journals, in fields such as sociology and ethnography I think you will find it is not unmoved by his inquiry. The style of reading alongside the actual transformations and revivals along with the doctrine of transcendental materialism, as a great move from the primitive Marxist position amount to a synthesis of Marxism and Hegel such as Marx himself never achieved.
By this I mean that Marx ignored Hegel's great and lasting insight that wisdom comes only with the dusk, claiming that, hither to the philosophers have only interpreted the world (the task is to change it), the discovery of Hegel was that this is impossible in the proper sense. However, Hegel could not finish his own objective work, since he did not live in this day, but his, he had in mind certain rational laws, but in order to delineate them one must live to see the way the society and culture unfold and make themselves know in actual terms and so Zizek as attempted such work. Perhaps very badly, but who knows?
Answer: Unfortunately, Žižek is misinterpreted and misunderstood very often. He is famous but this fame is rather only bringing a demise to his reputation and work. This is why most people consider him only the "Borat of Philosophy", and not a real philosopher. Furthermore, academia widely rejects him. It is because of these reasons that the true value of his work is not yet known and underestimated. Perhaps it is going to take few decades until we truly understand what huge contributions he has made to the field of philosophy [and psychoanalysis].
One of the most important known contributions of Žižek is the revival of dialectical materialism. I cannot recommend his extremely important and fascinating work Less Than Nothing: Hegel and the Shadow of Dialectical Materialism enough.
You are in particular asking about 'political philosophy' and that would be perhaps even harder to answer. In the 2005 documentary directed by Astra Taylor named "Zizek!, he himself mentions that he never truly enjoyed writing his political books. Nonetheless, he has offered great and unique insights into politics over the years. You can look into his book "Welcome to the Desert of the Real" as a start if you are in particular looking for his political writings.
The best way to explore Zizek is by reading his works and even watching his lectures/talks on YouTube, but I highly recommend you to read his books first and definitely watch "The Pervert's Guide to Ideology (2012)" and "The Pervert's Guide to Cinema (2006)".
Comment: There's also the plagiarism `dispute? debate? accusations?`... (http://www.critical-theory.com/slavoj-zizek-accused-of-plagiarizing-white-supremacist-magazine/)


iPhone 4 cracked and will not slide over for password.

Question: I cracked my iPhone 4 and now it's messed up. The phone turns completely on where i can see my lock screen picture, but if trying to sliding over to unlocked it..it won't slide. The only place I can get it to slide over from it the very top, but I'm unable to type the password because nothing works beyond the top part. Is this fixable? I just want my messages and photos back.
Answer: Man...that's rough.
If you have been backing up to iTunes or iCloud, your stuff should be there.  You are backing up, right?
There are a couple more options you can try before you take your iphone in for repair to get at your data:

Bluetooth Keyboard - just connect and enter your pin
Voice Over - triple tap the home button and "say" your pin

Both of those must have been previously set up.  If you didn't set them up, they aren't going to work.
One more you may want to try...
If either of those two methods are unavailable, try PhoneView which will allow you to get access to everything on your phone via your Mac.  It costs about $30, but that may be cheap considering how valuable your data is.
Finally, if all else fails, you will have to have the digitizer replaced.  Maybe a local repair shop can hook up a digitizer temporarily so you can back up your data, but that would be a long shot.


Chronological orders of dynasties and kings after Mahabharata as per Puranas

Question: Puranas list a number of kings and dynasties that will rule after Mahabharata. It looks like different Puranas list different kings. So, what happened in the history after Mahabharata in India as per majority of the Puranas? Pandit Kota Venkatachalam just provided wrong information if you look at various Puranas.
For example, he said Mauryas ruled for 316 years, while Puranas say they ruled for 137 years.
Comment: May be The difference are there  simply because of  copying errors or manual mistakes.
Answer: The query can be answered with reference to Srimad Bhagavatam.  Canto XII Chapter I enumerates the dynasties and their kings.  I give below the brief meaning without narrating words like son, brother, etc. I have also ignored the descriptions of the qualities and attributes of the kings as well as references to Kaliyuga and the declining morality and Dharmic qualities of the kings. I have covered verses 2 to 31, but by the 28th stanza I could not find corresponding English terms either in my vocabulary or in internet searches - any clarifications of such terms highlighted below would be most welcome and helpful to me too.
"As I have already clarified earlier in the Ninth Canto,in Jarasandha's lineage the last king will be Puranjaya. Puranjaya's  Chief Minister Shunaka will assassinate him and install his own son Pradyota as the ruler of Maghada. Pradyota Dynasty will rule for 138 years. The kings will be Pradyota, Palaka, Vishakayoopa, Rajaka and Nandivardhana.
Thereafter Shishunaga Dynasty will rule for 360 years.  The Kings will be Shishunaga, Kakavarna, Kshamadharma, Kshetragya, Vidhisara (Bimbisara), Ajatashatru, Dharbhaka, Ajaya, Nandivardhana (II) and Mahanandi.
Mahanandi also known as Mahapadma will be the last Kshatriya King. He will beget from his Shudra wife a son named Nanada who will succeed him. Nanda Dynaty will rule for 100 years and the rulers will be Nanda, Sumalya and his seven brothers.
Nanda dynasty will be destoyed by a Brahmin known variously as Chanakya or Kautilya whowill install the Maurya Dynasty on the throne. The Maurya Dynasty will rule for 137 years. The kings are Chandragupta, Varisara,Ashokavardhana, Suyasha, Sangata,Shalishooka,Somasharma Shatadhanva and Brihadhata. [As per Vishnu Purana Suyasha is succeeded by Dasharatha who in turn is succeeded by Sangata].
The commander - in - Chief of Brihadhata, Pushpamitra Shunga will assassinate him and install himself as the king. The Shunga Dynasty will rule for 112 years and its kings will be Pushpamitra, Agnimitra, Sujoyshreshta, Vasumitra, Pulinda, Ghosha, Vrajamitra, Bhagavata and Devabhuti.
Devabhuti will be assassinated by his minister Vasudeva Kanva who will install himsel the king.  The Kanva Dynasty will rule for 345 years and the rulers will be Vasudeva, Bhoomimitra, Narayana and Susharma.
Bali, a Shudra servant of Susharma will assassinate him and succeed him. The Bali Dynasty will rule for 456 years and its kings will be Bali, Krishna, Shreesantha, Pornamaasa, Lambodara, Chiblik, Meghaswati, Atmana, Anishtakarma, Holaya, Talaka, Purishbhiroo, Sunandana, Chakra, Shivaswati and his eight brothers, Gomtiputra, Purimaana, Medhashira,Shivaskanda, Yagyashree, Vijaya, Chandrayagya and Lomadhi.
Thereafter, seven Abhir Kings, ten Gardhabhi Kings, sixteen Kanka Kings, eight Greek Kings, fourteen Turk Kings, ten Garunda Kings and eleven Mauna Kings. These kings other than Maunas will rule for 1099 years, while the eleven Mauna kings will for 306 years.
I have not gone into the remaining 12 verses describing the other kings of Kali Yuga.  I hope, this answer is a satisfactory reply to your query.
Comment: I already read this. Waiting for other puranas like matsya Purana. Meanwhile who are those ten Gardhabhi Kings, sixteen Kanka Kings, eight Greek Kings, fourteen Turk Kings, ten Garunda Kings and eleven Mauna Kings? We are not studying in history books.
Comment: I have already stated that I  do not find any explanation with my Sanskrit Vocbulary or my internet search and have asked for inputs at the beginning of my answer :"I could not find corresponding English terms either in my vocabulary or in internet searches - any clarifications of such terms highlighted below would be most welcome and helpful to me too." I presume that repeating the question does not comprise the required input. Thanks anyway.


What is a one-bit ADC good for?

Question: I have recently heard of the concept of a one-bit ADC, and have seen it implemented in the context of a sort of digital-to-analog converter (oddly enough), and I'm wondering, what is the point? Why not simply use a higher-resolution ADC, if higher resolution is desired?
Answer: To give a basic example of how a 1-bit ADC can be used to obtain useful information from a waveform, take a look at this circuit. It uses a triangle wave to turn the information into a pulse width modulated output. This is a similar but simplified version of how other 1-bit ADC techniques work, by using a (usually fedback) reference signal to compare the input to.
Circuit

Simulation

Magnified Timescale View:

We can see from the top input waveform, the triangle wave is used to compare the waveform at different points through it's period. As long as the triangle wave is of a considerably higher frequency than the input (the higher the frequency the more accurate), this causes the comparator to output an average of high/low depending on the voltage level of the waveform.
To see how we can reproduce the original waveform from the PWM data, the comparator output is fed into a low pass filter, and out pops the sine wave again.
For further reading:
Delta-Sigma Converters
Successive Approximation ADC
Single Bit ADCs
Ramp Compare ADC (Counter ADC)
Answer: A one-bit analog to digital converter (A/D) is just a comparator with the threshold in the middle of the range.  Usually you don't call it a 1-bit A/D though, although it is legitimate to think of it that way.
There are ways to make use of a comparator to ultimately get a higher resolution digital value.  A delta-sigma A/D is one example.  This keeps integrating the comparator output and comparing it back to the analog input.  Over a number of bit times, the analog value is represented by the number of 1 bits out of the whole.  Resolution is a tradeoff with time.  Nowadays the bit rate can be in the multiple MHz range.  For example, at 10 MHz bit rate, getting a 20 bit result (about 1 M counts) would take 1/10 second.
Another example is a "tracking" A/D.  This contains a D/A and the comparator compares the D/A result with the analog input.  If the comparator result is low, the D/A value is incremented, otherwise it is decremented.
Comment: Delta sigma can also be viewed as an analog to PWM modulator.
Comment: How about linearity Olin? How does Delta-Sigma compare to various non-linearities of a regular n-bit ADC?
Comment: @jipp: Yeah, a delta-sigma A/D is backwards PWM.  The PWM generator is in the feedback path, so overall you find the duty cycle value to get the average level.
Comment: With second-order sigma delta you need far fewer bits (~ the square root), via some signal processing noise shaping magic that I don't fully understand.
Answer: One difference not yet mentioned between the terms "1-bit ADC" and "comparator" is that in many places where comparators are used, it is desirable to have hysteresis in an amount which is greater than the system's baseline noise level, but in applications that use a 1-bit ADC, such hysteresis is not wanted.
When constructing a multi-bit DAC or ADC, it is often difficult to ensure that each bit will have an effect precisely twice as big as the next lower one.  If the effect of a bit is larger or smaller than this, the difference in the voltages represented by between a code which ends in e.g. "0111" and the next higher code (which ends in 1000") will be incorrect.  If e.g. a 1mV change on an input sometimes causes a reported ADC value to change by 2 and sometimes causes it to change by 6, that can cause differential-feedback-based control systems to over-react to some changes and under-react to others.
Using a 1-bit ADC along with some analog electronics, it's possible to design a circuit so that the percentage of time a signal is high will depend upon the ratio between an input voltage and a reference voltage.  If one measures the percentage of time the signal is high, one may thus infer the input voltage.  In the absence of hysteresis or related effects, this measurement may be very accurate.  Hysteresis, however, may cause non-linearities which may be difficult to correct for.
Answer: Another name for a one bit ADC is a comparator. I can imagine 1 bit ADC may be enough for an application which needs to turn on/off a valve, switch, alarm if the signal goes above/below a threshold.
Comment: Definitely correct, but I think what I saw referred to as a "1-bit ADC" was more accurately described as a "delta-sigma ADC".

What is a one-bit ADC good for?


Is it possible to have windows which are independent of the workspace?

Question: What I am looking for is the ability of having independent windows that retain their type and shading/viewport settings when I change workspace. What seems to happen is that each workspace changes each of these independent windows to the last used state (or how you defined the startup file if you are just starting Blender). Is it possible to have windows not linked to workspaces? Thanks.
Comment: "View/Area/Duplicate area..." will give an independant window not related to the workspace..
Comment: Holy crap, lemon, I have a dual monitor setup, and you just saved me a lifetime of tab-switching! I've been using blender a long time, and never knew you could (or even thought to do) this. This deserves to be an answer in it's own right, in my opinion,
Comment: I think that's only possible with floating windows, for example the one that opens as the preference tab.
Answer: The "view/area" menus have a "duplicate area into new window" which gives an independant window that is not related to the workspace.
Comment: I'll add that once this new viewport exists, you can use the "editor type" selection button in the top left to make it any kind of editor window you want - Amazing for multi-monitor setups!


How to measure AC current in a wire without direct contact with the wire?

Question: I am building a power monitor project, and I want to measure the current flowing through the 230V mains supply to my house non-intrusively. I am aware of AC current clamps/transformers. I also came across hall effect current sensors like WCS1500. I've also thought about making my own current clamp. I'm not sure which is the cheap and efficent way to do this.
Answer: Depending on what the goals of the 'project' are, so what you build or buy, what you're intending to learn, a split core current transformer is hard to beat.
It can be very cheap if the core is salvaged from a dead transformer.
It's safe, as it clamps over a wire, and while a toroidal core could give slightly better performance, that would need a mains cable disconnected and reconnected to thread it through the core, not cool if you're monitoring the incoming to the house, but more practical if just monitoring a power strip.
As long as you assemble the core with good attention to getting minimum air-gap, it's very tolerant technically.
The output gain is calculable from first principles, knowing the number of secondary turns and having a small enough burden resistor. Compare measured and theory would be an interesting result of the project.
Answer: Safety and construction codes are intolerant of 'special' additions to
your house wiring, especially to the input side of your breaker box.   Standard approaches do exist, and an electrician can
install either current transformer(s) (with suitable mounting and enclosure)
or a second electric-utility-type meter.   Some of the 'smart' meters
run Linux and report by radio OpenWay Meter.
Usually, insurance and local ordinances will mean that inspectors
and licensed electricians will be involved.  Your local electric utility
will probably have to be consulted if the meter is to be pulled (detached) during
the installation.


Integral of $1/x$ about the asymptote with Cauchy versus complex

Question: In short, the integral of $1/x$ from $-2$ to $1$ or some other such range is being confusing for me. By means of the Cauchy principal value it receives a value of $-\ln 2$. Whereas with complex integration it would seem I'd get $-\ln 2 + \pi i$. And it can be shown decidedly that $\ln(|x|)$ does not have the derivative of $1/x$, but rather $\operatorname{sgn}(x)/x$. Basically what's the correct integral here?
Comment: Divergent integrals never have one "correct" answer. You have to choose the answer that makes the most sense for your application.
Comment: @icurays1 Why shouldn't they? Just because this has a singularity what makes it so special? Why not consider functions which have an 'asymptote' as you approach infinity. Something like $\frac{1}{1 - \frac{x}{x + 1}}$ is only undefined for an infinitely large x (and x <= -1 but ignore that for this example)
Answer: For a function with a singularity, integrals in the complex plane are in general path-dependent. Depending on what contour you take, you could get $-\ln 2 + k \pi i$ for any odd number $k$.
As for $\ln |x|$, that does not have a derivative at all in the complex sense.
The (complex) antiderivative of $1/x$ is $\ln(x) + C$, but this is multi-valued:
there is no antiderivative that is analytic on all of ${\mathbb C} \backslash \{0\}$.


How can the momentum in one direction flow into another?

Question: In the Stress-Energy tensor of General Relativity, the momentum density in one direction can flow into another, which is an object's shear stress. Still, how can the momentum travelling in one direction flow into another?
Comment: Just imagine I am running by you while you are standing still on a skateboard. While I am approaching you, I push you or pull you a little bit. What will happen to you? You will move toward me, right? You get some momentum. This amount of momentum is the flow of the momentum. This flow of momentum passes from me to you, in the direction orthogonal to my momentum. Although I am running ahead, the force exerted on you transfers the momentum, and thus the flow.
Comment: because space-time is curved...  Imagine a scenario in fewer dimensions
Answer: This has really nothing to do with general relativity or anything like that. It becomes much simpler if you remember that "flow of momentum" is another word for "force".
So consider this: you have a table on wheels. The top of the table is made of ice (so frictionless), except for one section which is regular wood and thus has friction. Sitting on the table on the icy part is a box.
You push the table. Initially the box stays in place, sliding over the ice since there is no friction to push it along. But when the box meets the wood, suddenly it is dragged along with the table thanks to friction. In effect, what you have done is transfer some $x$-momentum (i.e., horizontal) in the $y$ direction (i.e., vertically).
Answer: Although you have asked in the context of general relativity, this also occurs in continuum mechanics in which stress has the same interpretation, i.e. as momentum flux. Momentum density oriented in one direction flowing into another direction is a consequence of the way we set up the coordinate system. Suppose you orient your coordinate system such that its X-axis points along the direction of momentum density. Then momentum density will have only one non-zero component which is the X-component, and its flux will also be in the X-direction, with no flux in other directions.
But momentum density vector has different directions at different points. So usually we fix a coordinate system with given direction for its axes. In that case direction of momentum density can have arbitrary orientation and in general is not aligned with any of the coordinate axes. It is then that we have a component of momentum density in a particular direction flowing into other directions.


Is there any way to undo a merge on geni.com?

Question: Someone in my family tree accidentally merged two accounts on geni.com, is there any way this can be undone?
Answer: From http://help.geni.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=991:

Please note that a Tree merger is
  essentially the merging of two
  profiles in different Trees into one
  profile and Tree. Therefore, you can
  undo a merge only before the profile
  merger that connects the two tree has
  been completed. Once that profile
  merge has been completed, the trees
  are merged.
Please note that once you have merged
  your Trees it is irreversible.
  Therefore, it is important to pay
  closely examine which information you
  wish to keep, regarding each duplicate
  Profile. If the trees are already
  merged, you can use your Privacy and
  Family Group settings to manage
  privacy between the two sides of the
  family.
To reverse a merge, you will first
  need to add the deleted profile back
  to the Tree with the correct
  relationships. Once that is done, you
  can email firstname.lastname@example.com with a link to
  the merged profile and the incorrect
  relationships that remain on that
  profile.
Comment: That article was created in 2008, though, so I have no idea if that policy is still current.
Answer: On the Geni wiki I read that they're planning a "Tree split" option which would probably solve your problem.

Tree Merging is currently available.
  Tree splitting [1] will enable existing trees to split.

On the other hand it says quite clearly:

Once you have completed a merge:
  It cannot be undone

Source: Tree Merging


How can I make some themes usable only by admins?

Question: I want to restrict certain themes so they can only be usable by the an admin. If I network a theme then everyone has access to it. How can I do this?
Comment: Could explain what you mean with »usable«? Especially how should widgets and nav menus work?
Answer: Its built in that way so you can have themes only on specific blogs:

Disable the theme under Super Admin
-> Themes.
Enable the theme for one site under
Super Admin -> Edit the site you
want. Look on the top right, there's
a list of disabled themes.


Accessing custom (non-Java) artifact repository from Maven

Question: I'm looking for a way to access a custom, non-Java, artifact repository with Maven. We have an artifact repository consisting (more or less) of a bunch of zip files (containing native executables, header files, etc.) on a Windows share. These are accessed by a Ruby script which can materialize/unpack these artifacts as needed. There are also artifacts which are not stored on disk, but is materialized from other places (Subversion, for example).
I would like to be able to integrate these repositories into a Maven build, so that (for example) integration tests can use .exe and .dll files from the native artifacts. I've looked at Nexus and Artifactory, but it is difficult to tell how well they would suit this scenario. Most of the documentation around "custom layouts" seem to assume that we are talking about Java artifacts of some kind.
Comment: You married to Maven? Apache ivy has a standalone java client that just does dependency management. Ivy also supports more than just Maven repositories
Comment: Changing to something other than Maven is not an alternative at this point, no.
Answer: Forget the fact that these things are called "Maven Repositories", while Maven has a certain expectation of repository structure this same structure is also what is used by almost every other Java build tool that is out there.   Think of these things as general storage for artifacts with coordinates:  groupId, artifactId, version, qualifier.
A good repository manager doesn't care what you are storing in this repository.   It could be a ZIP file, an EXE, whatever you want to store.   All it cares about is that artifacts are stored in this repository structure.    What you end up when you use a repository manager is a collection of artifacts that are addressable by these coordinates.
I use a repository manager to do a number of things that have nothing to do with Java including storing ZIP files used in a deployment process.   I access my repository managers using curl.  In this case it can be viewed as a simple REST-accessible bit bucket that applies some structure to the files you are storing in it.
(Also, notice that my answer that isn't marketing for either Artifactory or Nexus. ;-)
Answer: The simplest solution here is to expose your repository via HTTP so that it just so happens to have the standard Maven layout and metadata.
If that doesn't work for you, you'll be learning about how to implement some pieces of Maven.
Answer: Artifactory is not tied in with Maven and can store and search any binary, regardless of layout (custom layouts are only needed if you like Artifactory to extract module information about your artifacts, which is used for version auto-cleanup, cross-layout transformations, etc.).
Since Artifactory is accessible purely with HTTP any build tool that can send GET and PUT queries (for resolve and publish, respectively) can talk to it.
One common use case is to use curl, but Artifactory also has nice OOTB integrations with leading CI tools for easy configuration-based resolution and publishing.
You may find this blog post helpful as a genreral information about running non-Java/non-Maven builds with Artifactory.


Outlier Robust Regression with Clustered Standard Errors

Question: I want to do a regression analysis with a dataset that consists of multiple subgroups so I have to use cluster robust standart errors. However, the dataset also has some extreme outliers and I want to deal with those using a outlier robust regression method. I am working with python statsmodels and I have noticed that the robust_linear_models.rlm method does not support cluster robust standart errors. I am wondering whether this is the case because it is not possible to have both cluster robust standart errors and an outlier robust regression or because this is not implemented in statsmodels.
Comment: It's possible based on general principles, but I didn't find much literature on it https://github.com/statsmodels/statsmodels/issues/1379
Comment: Is anyone aware of a function in a different language (e.g. R) that could do this?
Answer: I think I found out how to run such a regression in practice. One can use statsmodels RLM without cluster robust errors to get the weights assigned to each observation and then plug these weights into statsmodels WLS, which does support cluster robust standard errors. Since clustering only affects the significance but not the coefficients, the weights from the RLM regression without clustering should be correct.


Is there a Way to Retrieve a Lost/Forgotten KeePass Password?

Question: I recently decided to store all of my passwords in KeyPass Password Safe 2. I forgot my password to KeyPass.
Is there anyway to retrieve it? My assumption is no there is not for obvious reasons.
Answer: No.

If you forget this master password, all your other passwords in the database are lost, too. There isn't any backdoor or a key which can open all databases. There is no way of recovering your passwords.
Answer: If you've forgotten it because you just changed the master password, you can do what I do in the future:

Make a backup copy that uses the old password.  Make sure this has the new password in it.
Change the real copy to use your new password
Keep the one that uses the old password around until you know the new one so well you don't even have to think about it.  After that, delete it.

Hasn't steered me wrong yet.
Answer: If its correctly built (and by all accounts it is), your chances of recovering your password are very limited - luck, knowledge about yourself and your behaviour, you may be able to narrow down the key space and brute force it.  There are tools to brute force Keepass files - see here.   That said, its likely easier and faster to simply reset all your passwords.
Comment: I went to this link but  I can't get the way how to run brute force in keepassx. I noticed that the document are not written in English.
Answer: i did a quick web search for "brute force keepass".
this came as 3rd result, the 1st one i clicked.
https://rubydevices.com.au/blog/how-to-hack-keepass
i will simply copy it below, for redundancy.
enjoy it while enough links work. i've omitted a few and updated one that was broken.
i haven't tested any of this, but at least the idea is very clear and sound:
there is always a way.
copied
How to Hack KeePass Passwords using Hashcat
02 May 2017

Let's talk a little about passwords today. Have we all heard of the infamous LinkedIn password breach back in 2012? Over 117 million encrypted passwords were leaked and put up for sale.
Massive data dumps such as these become treasure troves for research of human behavior in the context of security. The US Company Preempt revealed that a staggering 35% of the passwords in the dump could already be found in password dictionaries available prior to the breach. Statistics like these remind us to keep our passwords as strong as possible.
Today we are going to perform a simple attack on a KeePass database file and attempt to break a master password. For those unfamiliar with the software, KeePass is a popular open source password manager. Say you have 50 different passwords for different purposes that you need to remember, how do you go about remembering them all? Some people will write them down in a book. Others may store them in a plain text file - definitely not recommended! A third approach is to use a software application like KeePass. What it does is encrypt all passwords provided to the tool using AES in combination with a master password and optionally a key file. When a user then wishes to recall any particular password they will provide their master password to the tool; in response, the tool will decrypt all passwords in plain text allowing the user to check the entry of their interest.
For the software system to verify the validity of the master password provided it will apply a hashing algorithm to the string given in concatenation with other data. All those who have meddled in the password cracking world know that whenever a hash is available a brute force or dictionary attack can be launched.
So how can we do this? The first step is to extract the hash out of the KeePass database file. Here is a KeePass database we created with a very simple password that we will use for the course of this tutorial.
There is no need to re-invent the wheel here. A utility called "keepass2john" is available from the John the Ripper github repository. Let's jump on a Linux box and install it as follows.
<code>[user]~$ git clone https://github.com/piyushcse29/john-the-ripper.git
[user]~$ cd john-the-ripper/src
[user]~$ make
[user]~$ make clean generic
[user]~$ cd ../run
</code>
Next, copy the KeePass database file to the current directory and run the "keepass2john" binary on it.
<code>[user]~$ ./keepass2john CrackThis.kdb > CrackThis.hash
[user]~$ cat CrackThis.hash
CrackThis:$keepass$*1*6000*0*dfb86938fedd22b8235c4de4b02e5bb3*c292fa502cbb0e912f30c1e1b6829a2c04ebe30477cb269d462fbbbeeb9360a6*b85fb0e07f3edbd4123db2c829b79355*6d4857a728900d4da4fad66999233e5c647e5354330d31be3a47bbdd102a5ca7*0*CrackThis
</code>
We now have our extracted hash file ready to be cracked. The next step is to download a password cracking utility. The greatest by far is Hashcat available from here. What makes Hashcat the leader of such tools is its massive collection of predefined hashing algorithms and its ability to utilize a computers GPU to increase cracking speeds by an enormous degree.
As of Hashcat version 3.0 the software supports KeePass with no custom algorithms needed to be defined. We can run a quick grep command to learn the switch value of 13400 needed for our invocation of the binary.
<code>[user]~$ ./hashcat --help | grep -i "KeePass"
13400 | KeePass 1 (AES/Twofish) and KeePass 2 (AES) | Password Managers
</code>
Next, we need to make an edit to our hash file. The hashcat binary does not expect the name of our KeePass database to be pre-pended to our hash so we will have to trim the string with a text editor; after doing so our hash file will look as follows.
<code>[user]~$ cat CrackThis.hash
$keepass$*1*6000*0*dfb86938fedd22b8235c4de4b02e5bb3*c292fa502cbb0e912f30c1e1b6829a2c04ebe30477cb269d462fbbbeeb9360a6*b85fb0e07f3edbd4123db2c829b79355*6d4857a728900d4da4fad66999233e5c647e5354330d31be3a47bbdd102a5ca7*0*CrackThis
</code>
We may now launch our attack. We used a password dictionary we picked arbitrarily called "cracklib-words" available from here (updated).
<code>[user]~$ # -m 13400 => KeePass Hash Provided
[user]~$ # -a 0 => Dictionary Attack
[user]~$ # -w 1 => Low Latency Desktop Profile
[user]~$
[user]~$ ./hashcat -m 13400 -a 0 -w 1 CrackThis.hash cracklib-words
</code>
Our machine proceeded to crack the master password in 12 minutes with the following results.
<code>Session..........: hashcat
Status...........: Cracked
Hash.Type........: KeePass 1 (AES/Twofish) and KeePass 2 (AES)
Hash.Target......: $keepass$*1*6000*124*dfb86938fedd22b8235c4de4b02e5b...
Time.Started.....: Mon May 1 20:53:17 2017 (12 mins, 8 secs)
Time.Estimated...: Mon May 1 21:05:25 2017 (0 secs)
Guess.Base.......: File (cracklib-words)
Guess.Queue......: 1/1 (100.00%)
Speed.Dev.#2.....: 1463 H/s (1.85ms)
Recovered........: 1/1 (100.00%) Digests, 1/1 (100.00%) Salts
Progress.........: 1064960/1671704 (63.71%)
Rejected.........: 0/1064960 (0.00%)
Restore.Point....: 1054720/1671704 (63.09%)
</code>
So what was the password you may ask? Sorry, if you want to know that you are going to have to crack it yourself :) Thanks for reading.
Always,
Ruby Devices


How to accomodate a large set of filter controls horizontally on a page?

Question: Since the left column is occupied by the left navigation, this leaves only the middle area for placing filter controls. But there is a need to provide for more filtering options in future. In such a scenario, how to accommodate the filter controls in the limited area? Is it advisable to use a scroll (vertical/horizontal) or a chevron or something else?
Answer: I guess Ryan option will be fine if the search is not the main feature on the site, let me explain.
The point is that in order to plannify the best way to display the filters you need to think on user behaviour...

If the main feature on the page is search and users will need to search frecuently and using several filters to hide some of them is not a good idea, user will need to have filters visible and handly because they need to now wich criteria are available to add. In this event you need to find a way to display all filters together.
Also I do not recommend use scroll on filters area, if a user select something on an input and then scroll down and the input is not visible he will need to scroll up and down (or left and right) in order to see what he is writting... this may make them goes crazy.

I've being thinking on how to gain space without scroll neither advanced search option and I have a "crazy" idea... I add here a mockup of the different steps:

This need a deep analisys but I guess it will be a cool way to display a search tool, anyway if you plan to use it I suggest to create a detailed prototype and test in deep before adding it to the final product.

If the search is going to be done not so frequently and it's not the main feature on the page you may try to define main filters and keep visible just 2 or 3 and hide others on the advanced filters layer. In this event the solution suggested by Lie may be good (ie: http://awesomescreenshot.com/076j64ff2)

Hope this may help you :)
Comment: appreciate your time and effort in visualizing an alternative. Would this work when each filter (field) has predefined options from which the user has to select one or more options?
Comment: Hi Kartik, this still need some time of brain to be well defined but I guess it will work, as you are displaying the input in a layer you can add there whatever you need (dropdown menu with predefinied options, multiselect, checkbox select...) Another thing I guess need to be added is an option to edit / delete next to the selected criteria to allow user to easily change or delete it. :)
Comment: +1 Though I do hope I can click the tick? So I can change the value to search for?
Comment: Cool way to solve this Marjan, then maybe we need to clarify by using a differente icon which clarely say "ey click to edit guy" :) Thanks!
Comment: Now I want to be able to search for tall authors.
Answer: Hide all but 2-3 most common filter options, and put an advanced filtering option on a separate page.
Comment: @Kartik G: the most common filter is usually a no-brainer uber-textbox that will search on all criterias, like Google search. For the common case, the user shouldn't need to think which filter they should use.
Comment: Yes this could be one way, though then it requires deciding what filters to include upfront.
Comment: Great point there about not making the user think too much about filters.
Comment: @KartikG, making those decisions is a part of our responsibility and our role
Answer: First up you need to think about your minimal case, that is users using only 1 filter.  For this the search section must be a UI that most users are used to already (like the google search ui). Only then we evolve the idea and provide controls for multiple filters.

Below,

Click on add 'another filter' and you can select from the criteria like 'name,gender,age'
Based on the selection we provide either a text/dropdown field.

Here, you are not restricted by the number of filters (it'l just be a longer drop down list) and the scroll significantly increases only when the users have a LOT of filters in place.
additionally, a checkbox to temporarily disable a filter and search.
Answer: For a feature rich implementation of faceted
search and navigation, see [http://
mspace.fm/](http://
mspace.fm/) and try the demo button at top
right.
Here they have a very dynamic horizontal faceted search facility where you can pick and choose from a variety of categories to show initially or for the user to switch around. You could choose the most likely core facets to start with.
Answer: I am looking into having all my filter criteria in a page-wide accordion. It would open when they click it and then show all my criteria then they can also close it once they select their criteria. The selection auto-filters the data.


How to use memcached with Joomla

Question: How can I use memcache in Joomla?  I'm a newbie in this field so please be descriptive with your answer.
Comment: @Andre Joomla's core has a caching layer that implements memcached, XCache, and flat file caches among others. The Joomla Framework has a caching class where you send in a key-value pair, then it handles the caching depending on which driver has been selected in the configuration. There is absolutely no need to hack Joomla to add memcached; it's already built in.
Comment: Do you *need* memcached?
Comment: IMHo sites that are using memcached usually should stay away from Joomla or any boxed CMS for that reason. the reason would be - to implement memcached -  you would have to change source php code (perhaps drastically sometimes). Joomla (or any other boxed CMS) have been designed for folks who'd rather design a template instead of changing source code. Also -  you really should not change Joomla's core php as it 'll be rather a hack and you would have problems updating in the future which will make your site VERY easy to hack. Use memchached only if you have a cluster.
Answer: You will need to install memcached on your server and will probably need root access to do so.  You can get memcached from http://www.danga.com/memcached/. It requires libevent, which can be downloaded here: http://www.monkey.org/~provos/libevent/
Finally, you'll need to get the PHP PECL extension for memcache. To install this, you need to go to the server where PHP is installed and run this command:
pecl install memcache

Again, you will most likely need root access to your server to do this. After you have libevent, memcached, and the PECL extensions installed, go to the Global Configuration in Joomla and choose Memory Cache as the Cache Handler under Cache Settings. After you save the Global Configuration, open it again and more inputs should appear underneath the Cache Handler input. Set Memory Chache Server to localhost and the port to 11211. This should match the parameters you use to run memcached from the command line.
EDIT: You can also use XCache not only to store data in a way similar to Memcache, but it will also cache the opcode generated by PHP. This way, instead of reading the PHP code from disk and parsing it each time, it will hold the code in memory for the next request.
Be sure to select XCache as the Cache Handler in Global Configuration. Read this for information on installing XCache: http://xcache.lighttpd.net/wiki/InstallFromSource
Answer: In order to make Joomla to use memcache for session caching you need to manually edit the configuration.php and change this line:
public $session_handler = 'database';

to this one:
public $session_handler = 'memcache';

And this is what is missing everywhere, you need to add a new option memcache_settings:
  public $memcache_settings = 'a:3:{s:10:"persistent";s:1:"0";s:11:"compression";s:1:"0";s:7:"servers";a:1:{i:0;a:2:{s:4:"host";s:9:"127.0.0.1";s:4:"port";s:5:"11211";}}}';

This is a serialized multy-dimentianal array. I use this code to generate the above string:
 $a = array(
   "persistent" => "0",
   "compression" => "0",
   "servers" => array(
     "0" => array(
       "host" => "127.0.0.1", "port" => "11211")
     )
   );

echo(serialize($a));

If you don't add the memcache_settings option your sessions will never work with memcache.
Answer: These settings in configuration.php work for memcached in Joomla 3.3+
public $cache_handler = 'memcached';
public $memcached_server_host = '127.0.0.1';
public $memcached_server_port = '11211';
public $memcached_persist = '1';
public $memcached_compress = '1';
public $cachetime = '15';
public $session_handler = 'memcached';
public $session_memcached_server_host = '127.0.0.1';
public $session_memcached_server_port = '11211';

To install memcached on a Debian system:
apt-get install memcached php5-memcached

(you can also use memcache in place of each occurence of memcached in the above public variables & install the older php5-memcache extension)
Upgrading to php5.5 will give you a builtin Zend Opcode Cache - this could be used with APCu  (APCu is the Alternative PHP Cache with the Opcode Cache removed) - to cache userland locally if you do not need a distributed memory cache (memcached)
For a single VPS APCu has a lower memory footprint & is a more suitable cache (especially with php5.5) & can be set in configuration.php with:
public $cache_handler = 'apc';
public $session_handler = 'apc';

Answer: This how to might also offer some help for Joomla 2.5 as it points to the Joomla Admin Screen to use memcache http://www.siteground.com/tutorials/supercacher/joomla_memcached.htm
Answer: It's better to not use APC for backend cache. This can cause a lot of fragmentation. I have only seen it degrade performance of Joomla.

How to use memcached with Joomla


What champions scale the best in League of Legends

Question: In League of Legends I know different champions have different strengths in the game. I want to know what champions, maybe top 20, scale the best. This means that they are weak early but are strong later in the game. Example: Kayle is a champion that at level 1 has melee attacks and does little damage, but at level 6, 11, and 16 she gets stronger like more attack speed, ranged attacks, and waves of damage. I want to know if other champions scale like this.
Comment: Do you want to know which champions scales with levels? Or by any means? I guess that the hyper carry archetype may be what are you looking for. A good portion of adc start weaker but became killing machines if they reach full build. But it's about the items, not the levels. There are some champions wich get special bonuses at certain levels ( other the normal abilities upgrade )
Comment: @Fredy31 It is possible to answer the question statistically as riot has win rate by game length stats.
Comment: @ChunYin yes please do
Answer: Level dependant gameplay : Gangplank, Illaoi, Kayle
These three champions have a scaling mechanic tied to their level.

As the OP wrote, Kayle AA get special effect on level 6 / 11 / 16 which changes greatly her power level.
Illaoi tentacles spawn and hit quicker at lvl 7 and 13, which give her a good powerspike at those levels.
Gangplank has the same kind of step up at 7 and 13 with his powder kegs loosing health much quicker, allowing some swift and powerful combos not possible earlier.

Infinite scaling : Bard, Cho'Gath, Kindred, Nasus, Senna, Shyvana, Thresh, Veigar
I won't detail all of them but each of them has an infinite scaling mechanic in their kit.

Bard (meeps), Kindred (marks), Nasus (stacks), Senna (souls), Thresh (souls) and Veigar (evil power) can all gain damage nearly indefinitely

Cho'Gath (R), Shyvana (passive), Thresh (souls) can all gain survivability nearly indefinitely

If further informations are needed, do not hesitate to visit the wiki to consult these champions abilities here
A lot of champions need their 6th level
Kassadin is the best example in my mind. He's not too weak early but his R changes drastically his threat level. Same thing for Malzahar, Mordekaiser or Skarner.
Honorable mention : Zeri
With her ultimate ability, Zeri can gain infinite movement speed.
Check on the wiki or Youtube if needed.
I won't get into build dependent scaling
They are highly dependent on champion, matchups, skill, team comp. Just know that a full stuff ADC is a killing machine.
And I probably forgot some so do not hesitate to suggest edits.
Answer: The answer will change every other patch. To find out the current meta for late game champions and for a more statistical approach to this question, you can refer to this graph on lolalytics (and some other stat sites).
Example: Rek'Sai is notorious for being a menace early and falling off after players start grouping up. It's well represented in her chart.

Similarly, Kassadin who's infamous for being a late game champion has his win rate climb up steadily throughout the game.

League has an API for this which lolalytics is using to get it's data, you can probably write one on your own to compare it as well.