How to rotate without using built-in functions?

Hi, I'm trying to write a function that will take an input matrix and rotate it 180 degrees to provide and output matrix. Here is what I have so far:

function [out]=matrix180(in)

[row,col]=size(in);

for m=1:length(row)
    for n=1:length(col)
       out(n,m)=in(m,n);
    end
end

The problem I keep having is that the matrix returned does not have the same dimensions as the input, i.e. if the input is 465x500, the output is always only 1x1. Additionally, because of this issue, I don't know if the output will actually be rotated by 180 degrees or not. How can I tell how much I am rotating my matrix by looking at my code?

[Luna]

You don't need to use length because row and col already 1x1 double which gives you the row and column number. So when you say length(row) -> this gives 1.

Here:

function [out]=matrix180(in)
[row,col]=size(in);
for m=1:row
    for n=1:col
       out(n,m)=in(m,n);
    end
end

[Martine Delgado]

Ah I see.. thank you! That addressed my size of having a 1x1 matrix. Now how can I rotate it so that I have an input of mxn and an output of nxm...

[Walter Roberson]

Are you rotating by 90 degrees, or by 180 degrees?

[Walter Roberson]

Consider

a b c
d e f
g h i
j k l

your code would create

a d g j
b e h k
c f i l

whereas a 90 degree rotation counter-clockwise would produce

c f i l
b e h k
a d g j

and a 180 degree rotation would produce

l k j
i h g
f e d
c b a

Answer 1

[Walter Roberson]

Do not loop to length(row) and length(col), loop to row and col . row and col are both scalars, so length() of them is just 1.

Note: your code transposes, not rotates by 90 degrees and certainly not 180 degrees.