function a = i4col_swap ( m, n, a, i, j ) %*****************************************************************************80 % %% I4COL_SWAP swaps columns I and J of a integer array of column data. % % Example: % % Input: % % M = 3, N = 4, I = 2, J = 4 % % A = ( % 1 2 3 4 % 5 6 7 8 % 9 10 11 12 ) % % Output: % % A = ( % 1 4 3 2 % 5 8 7 6 % 9 12 11 10 ) % % Licensing: % % This code is distributed under the GNU LGPL license. % % Modified: % % 19 February 2005 % % Author: % % John Burkardt % % Parameters: % % Input, integer M, N, the number of rows and columns in the array. % % Input, integer A(M,N), an array of N columns of length M. % % Input, integer I, J, the columns to be swapped. % % Output, integer A(M,N), the array, with columns I and J swapped. % if ( i < 1 | n < i | j < 1 | n < j ) fprintf ( 1, '\n' ); fprintf ( 1, 'I4COL_SWAP - Fatal error!\n' ); fprintf ( 1, ' I or J is out of bounds.\n' ); fprintf ( 1, ' I = %d\n', i ); fprintf ( 1, ' J = %d\n', j ); fprintf ( 1, ' N = %d\n', n ); error ( 'I4COL_SWAP - Fatal error!' ); end if ( i == j ) return end col(1:m) = a(1:m,i)'; a(1:m,i) = a(1:m,j); a(1:m,j) = col(1:m)'; return end