/**
 * This program finds the transpose of a matrix entered by the user.
 * The main method asks for the user to enter a matrix, and then calls
 * transpose() to do the transposition.  The result matrix is then
 * printed.
 */

class Transpose
{
    public static void main (String[] args)
    { 
       // DECLARE VARIABLES/DATA DICTIONARY

        int[][] a;      // GIVEN:   A matrix of integers
        int nRows;      // GIVEN:   Number of rows in a.
        int nCols;      // GIVEN:   Number of columns in a.
        int[][] at;     // RESULT:  Transpose of a


        // PRINT OUT IDENTIFICATION INFORMATION
        
        System.out.println();
        System.out.println("ITI 1120 Fall 2006, Lab 10, Example 2");
        System.out.println("Name: Diana Inkpen, Student# 123456");
        System.out.println();


        // READ IN GIVENS

        System.out.println( "Enter the number of rows in matrix A:  " );
        nRows = ITI1120.readInt( );
        System.out.println( "Enter the number of columns in matrix A:  " );
        nCols = ITI1120.readInt( );

        a = MatrixLib.readIntMatrix( nRows, nCols );
        
        // BODY OF ALGORITHM
     
        at = transpose( a );

        // PRINT OUT RESULTS AND MODIFIEDS

        System.out.println( );
        System.out.println( "The transposed matrix AT is: " );
        System.out.println( );
        MatrixLib.printMatrix( at );

    }

    // If the 'main' method calls other algorithms, put the method(s) below.

    /**
     * This method transposes matrix 'a', returning matrix 'at'.
     *
     * Matrix a is assumed to be rectangular. The dimensions are not passed
     * as parameters; instead, the dimensions are determined from the
     * array lengths.
     * 
     * GIVENS:  a:  an nRows x nCols matrix containing integers
     */

    public static int[][] transpose( int[][] a  )
    {
        // DECLARE VARIABLES / DATA DICTIONARY

        int nRows;   // GIVEN:  number of columns in a, rows in b
        int nCols;   // GIVEN:  number of columns in b and c
        int[][] at;  // RESULT:  the transpose of matrix a
        int tRow;    // INTERMEDIATE:  index for row position in at
        int tCol;    // INTERMEDIATE:  index for column position in at
        
        // BODY OF ALGORITHM

        nRows = a.length;       // number of rows in a
        nCols = a[0].length;    // number of columns in a:  this uses the
                                // assumption that the matrix is a rectangle
                                // so we can can use the length of any row.

        // Create result matrix.  Be careful with dimensions!
        
        at = new int[nCols][nRows];

        // Loop through each matrix position in at:

        for ( tRow = 0; tRow < nCols; tRow = tRow + 1 )
        {
            for ( tCol = 0; tCol < nRows; tCol = tCol + 1 )
            {
                at[tRow][tCol] = a[tCol][tRow] ;
            }
        }

        // RETURN RESULT

        return at;
    }
                    
}