Sin along a vector? I have a 2D vector that I currently use to plot a line in its direction. 
I calculate the next point using:
p_new = p_old + v * i

Were i going from 0 to some upper limit where the line should end, say for example 100.
How would I go about to plot a sin curve in direction v? 

Calculate the perpendicular $v^{\perp}$ to $v$ and normalize both vectors. Then plot
$$A\sin(\omega t)v^{\perp} + tv$$
for some values of the constants $A$ and $\omega$, which control the amplitude and frequency of the sine wave respectively.
