problem with passing reference of vector as function parameter

[LB34]

Hi, I'm a newbie in C++. I'm facing weird behavior when pass a vector as reference to my function. Here's the code snippet:

void TransposeMatrix (vector<int> &matrix, int N, int M)
{
	assert ( N != M );
	for(int i = 0; i < N*M - 1; i++) 
	{
		int oldPos = i ;
		int newPos = (N*oldPos) % (N*M - 1);
		while ( newPos != i ) {
			matrix [newPos] = matrix [oldPos];
			oldPos = newPos;
			newPos = (N*oldPos) % (N*M - 1);
		}
		matrix [i] = matrix [oldPos];
	}
}
 
int main()
{
	int row, col ;
	cin >> row >> col ;
	vector <int> A (row * col);	

	for(int i = 0; i < row; i++)
		for(int j = 0; j < col; j++)
			cin >> A [i*col + j] ;

	TransposeMatrix (A, row, col);
	
	for(int i = 0; i < col; i++) {
		for(int j = 0; j < row; j++)
			cout << setw(3) << A [i*row + j] << " ";
		cout << endl;
	}

	return 0;
}

In this program, the function is modifying the content of vector<int> &matrix. Hence, I need to pass a reference. However, the program gives bizarre output. You can see the program output here : http://ideone.com/ct28w

The surprising fact is that when I pass the matrix as value, it shows correct output. You can see the program output here : http://ideone.com/a3UkO

Btw, this is not any homework problem. So, please help me with your suggestions. Thanks in advance.