Question

I want to transpose a matrix, its a very easy task but its not working with me :

UPDATE

I am transposing the first matrix and
storing it in a second one
The two
arrays point to the same structure
I
need two arrays (target and source)
so I can display them later for
comparison.

struct testing{
  int colmat1;
  int rowmat1;
  float mat[64][64];
};

int testtranspose(testing *test,testing *test2){
  int i,j;
  test2->colmat1 = test->rowmat1;
  test2->rowmat1 = test->colmat1
  for(i=0;i<test->rowmat1;i++){
    for(j=0;j<test->colmat1;j++){
      test2->mat[i][j] = test->mat[i][j];
    }
    printf("\n");
  }
}

I thought this is the correct method of doing it, but apparently for a matrix such as :

1 2
3 4
5 6
7 8

I get :

1 2 0 0
3 4 0 0

What is the problem ?

Please help,
Thanks !

Answer 1

To transpose the matrix, you need to change rows and columns. So you need to use:

targetMatrix[i][j] = sourceMatrix[j][i];

Note how the order of i,j is changed, since one matrix’s rows are another’s columns.

By the way, instead of (*a).b, you can write a->b. This is the normal way of accessing a field of a struct pointer.