How to draw or plot illustrative figures? stackexchange users
I would like to plot or draw some illustrative figures for my research paper. I've tried GeoGebra already. But couldn't draw them as I wanted.
So my question is How can I draw them?
Or would you tell me what are their functions so that I can plot them in Matlab?
I post the figures in here, so that you can understand what am I looking for. 
Thanks for your reply.
P.S. If I am in a wrong forum please help me to find the appropriate forum for asking this question.




I like the program Asymptote. See a tutorial and a gallery of examples. Also, you can see the drawing in Calculating line integrals via Stokes theorem.
