plot a function in 3D

I have variables a and b both defined in [-1,+1] and the function c = a / (a + b)

How can I plot c in 3D to visualize the function?

Answer 1

[Walter Roberson]

RESOLUTION=20;   %increase this for a finer grid
t = linspace(-1,1,RESOLUTION);
[a,b] = ndgrid(t,t);
c = a./(a+b);
surf(a,b,c);

It is, however, not possible to plot it as a continuous surface, as your graphics display only has discretized output locations ("pixels").

[Dimitris]

the result does not look correct plus where I do exactly the same for

t = linspace(0,1,RESOLUTION);

i get a different result for that part of the graph

[bym]

why do you think it does not look correct?

[Dimitris]

it is correct. the resolution is too coarse and confused me. thanks for your help.

Answer 2

[bym]

a= rand(10,1)*2-1
b=rand(10,1)*2-1
c=a./(a+b)
scatter3(a,b,c)

[Dimitris]

thanks, but can I plot it as a continuous surface. For all values, not just random samples?