Plotting a function...

I have the following function that I would like to plot.

    Gamma = atand((Y)/(X));

Whats the best way to preform this task. Y and X will vary from 0 to 40.

Thanks,

Answer 1

[Walter Roberson]

[X,Y] = meshgrid(0:.1:40, 0:.1,40);
surf(X, Y, atand(Y ./ X));

[Matt Tearle]

Snap!

[Paulo Silva]

why not plot3 instead of surf?

[Walter Roberson]

Not plot3 because X and Y are both varying from 0 to 40, which makes this a question in which there is a Gamma defined over an area. plot3 is not suitable for drawing such things. In some cases something like a waterfall plot would be appropriate, but in such cases there are often specific graph calls.

[Paulo Silva]

Thanks Walter

[Walter Roberson]

By the way: in general, when you are working with arctan, it is better to use atan2(Y,X) rather than atan(Y./X), as atan2 gets the sector right. Unfortunately there is no atan2d (degrees), so I would recommend atan2 followed by a conversion to degrees.

[Walter Roberson]

atan2(0,0) also returns the desired 0, whereas atand(0./0) is going to return nan.

[Matt Tearle]

plot3 is for a curve in space - for each x there's one corresponding y and z, as opposed to a surface where there's a whole range of y values for each x (and vice versa)

[Paulo Silva]

thank you Walter and Matt for sharing your knowledge :)

Answer 2

[Matt Tearle]

[x,y] = meshgrid(0:0.5:40);
gam = atand(y./x);
surf(x,y,gam,'linestyle','none')

Answer 3

[Mark]

Thanks for the help