MATLAB Answers

0

Creation of matrix from loop

Asked by Renjith V Ravi on 17 Sep 2016
Latest activity Commented on by Star Strider
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).

  0 Comments

Sign in to comment.

1 Answer

Answer by Star Strider
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')

  4 Comments

Show 1 older comment
Star Strider
on 17 Sep 2016
Your ‘m’ matrix already is (256x256).
Check:
m_size = size(m)
m_size =
256 256
Yes, But m = (R+C).^2 . I just want to merge r and c to form a matrix of size 256x256
Star Strider
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.

Sign in to comment.