plotting 3d graph in matlab

Question

sumeet 2017-9-30

关闭： MATLAB Answer Bot 2021-8-20

hi,

I want to plot a function on z axis x and y can vary from 0 to 1 .

Two constants c_one and c_two are fed by user.

f(z)=(c_one*x + c_two *y)/(x+y)

So I tried

[X,Y] = meshgrid(0.1:0.1:1,0.1:0.1:1);

Z = ((0.9*X) + (0.1*Y))/(X+Y);

Here i took c_one=0.9 , c_two=0.1

It should simply evaluate z for 100 pairs of (x,y).

I get the message

Warning: Matrix is close to singular or badly scaled. Results may be inaccurate. RCOND = 5.473412e-19.

Why does that happen ?

Also , can you suggest a better way to graphically show 100 values (I did surf(X,Y,Z)) ?

Thanks.

Answer 1

Star Strider 2017-9-30

Use element-wise operations:

c_one=0.9;
c_two=0.1;
f = @(x,y) (c_one.*x + c_two.*y)./(x+y)
[X,Y] = meshgrid(0.1:0.1:1,0.1:0.1:1);
Z = f(X,Y);
figure(1)
surf(X,Y,Z)
grid on

See the documentation on Array vs. Matrix Operations (link) for details.