## Creation of matrix from loop

### Renjith V Ravi (view profile)

on 17 Sep 2016
Latest activity Commented on by Star Strider

### Star Strider (view profile)

on 17 Sep 2016
The following is a code for creation of matrix using for loop
for r = 1:256;
for c=1:256;
m(r,c) = (r+c)^2;
end;
end;
disp(m)
In m(r,c) = (r+c)^2; Suppose, if there are two or more equations like (r+c)^2 and (2r-c)^2 and (r+3c) ,I want to get m(r1,c1)=(r+c)^2 and m(r2,c2)=(2r-c)^2 and m(r3,c2)=(r+3c) and again m(r4,c4)=(r+c)^2 and m(r5,c5)=(2r-c)^2 and ...... etc upto m(r256,c256).

### Star Strider (view profile)

on 17 Sep 2016

I am not certain what you want to do, and you do not say what ‘(r2,c2)’ and the rest are, or what you want to do with them.
You can eliminate the loop with meshgrid:
r = 1:256;
c = 1:256;
[R,C] = meshgrid(r,c);
m = (R + C).^2;
figure(1)
meshc(R, C, m)
grid on
xlabel('\bf\itr')
ylabel('\bf\itc')
zlabel('\bf\itm')

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Star Strider

on 17 Sep 2016
Check:
m_size = size(m)
m_size =
256 256
Renjith V Ravi

### Renjith V Ravi (view profile)

on 17 Sep 2016
Yes, But m = (R+C).^2 . I just want to merge r and c to form a matrix of size 256x256
Star Strider

### Star Strider (view profile)

on 17 Sep 2016
My code does exactly that, without the loop.
Run my code and compare the figure it produces (in figure(1)) with the figure your code produces (in figure(2)):
for r = 1:256;
for c=1:256;
m(r,c) = (r+c)^2;
end;
end;
figure(2)
meshc(m)
grid on
The result is the same, the only difference being that my code is more efficient and easier to work with.