Polar Plot Design Issues


While looking over the polar plot code I came across the following issue: When plotting something like 'polar( [2*pi/180, 358*pi/180], [2.0, 1.0] )' the plotted line will actually wrap around the origin of the plot before reaching its destination. Initially I thought that this was correct behavior. The line numerically passed through all angles between 2 and 358 degrees in a linear fashion. However after consulting several colleagues and text books I believe that the behavior is actually wrong.

It is my understanding that for polar plots there is no linear mapping of the axes as it is currently implemented. Rather for a simple two-point line defined in polar coordinates, the line should essentially take the direct route. This is highlighted by the two-point equation of a line for polar plots:

r = ( r1*r2*sin(t2-t1) ) / ( (r1*sin(t-t1)) - (r2*sin(t-t2)) )

If you were to plug in the two points given above, then increment theta (t) from 2 degrees to 358 degrees, then convert to Cartesian cords, and plot the results, you will get the correct line that directly crosses the zero degree line and not one that wraps around the origin.

Is the polar plot function implemented this way on purpose? Which way should it really be implemented?

--James Evans