# include <stdio.h>

//
//  Program 8.13a, Stephen Kochan, Programming in C.
//
int main ( void );
void scalarMultiply ( int nRows, int nCols, int matrix[nRows][nCols], int scalar );
void displayMatrix ( int nRows, int nCols, int matrix[nRows][nCols] );

int main ( void )
{
  int sampleMatrix[3][5] = 
  {
    {  7, 16, 55, 13, 12 },
    { 12, 10, 52,  0,  7 },
    { -2,  1,  2,  4,  9 }
  };

  printf ( "Original Matrix:\n" );
  displayMatrix ( 3, 5, sampleMatrix );

  scalarMultiply ( 3, 5, sampleMatrix, 2 );

  printf ( "\n" );
  printf ( "Multiplied by 2:\n" );
  displayMatrix ( 3, 5, sampleMatrix );

  scalarMultiply ( 3, 5, sampleMatrix, -1 );

  printf ( "\n" );
  printf ( "Then multiplied by -1:\n" );
  displayMatrix ( 3, 5, sampleMatrix );

  return 0;
}

void scalarMultiply ( int nRows, int nCols, int matrix[nRows][nCols], int scalar )
{
  int row, column;

  for ( row = 0; row < nRows; row++ )
  {
    for ( column = 0; column < nCols; column++ )
    {
      matrix[row][column] = matrix[row][column] * scalar;
    }
  }

  return;
}

void displayMatrix ( int nRows, int nCols, int matrix[nRows][nCols] )
{
  int row, column;

  for ( row = 0; row < nRows; row++ )
  {
    for ( column = 0; column < nCols; column++ )
    {
      printf ( "%5i", matrix[row][column] );
    }
    printf ( "\n" );
  }

  return;
}