Lecture Notes on 22 Mar 2013

public class TestArray
{
  public static void rowSum (int[][] a)
  {
    for (int i = 0; i < a.length; i++)
    {
      int sum = 0;
      for (int j = 0; j < a[i].length; j++)
      {
        sum += a[i][j];
      }
      System.out.println (sum);
    }
  }

  public static void colSum (int[][] a)
  {
    for (int j = 0; j < a[0].length; j++)
    {
      int sum = 0;
      for (int i = 0; i < a.length; i++)
      {
        sum += a[i][j];
      }
      System.out.println (sum);
    }
  }

  public static int[][] transpose (int[][] a)
  {
    int[][] b = new int[a[0].length][a.length];
    for (int i = 0; i < b.length; i++)
    {
      for (int j = 0; j < b[i].length; j++)
      {
        b[i][j] = a[j][i];
      }
    }
    return b;
  }

  public static int[][] addMatrix (int[][] a, int[][] b)
  {
    int[][] c = new int [a.length][a[0].length];

    for (int i = 0; i < a.length; i++)
    {
      for (int j = 0; j < a[i].length; j++)
      {
        c[i][j] = a[i][j] + b[i][j];
      }
    }
    return c;
  }

  public static int dotProduct (int[][] a, int[][] b)
  {
    int sum = 0;
    for (int i = 0; i < a.length; i++)
    {
      sum += a[i] * b[i];
    }
    return sum;
  }

  public static int[][] mult (int[][] a, int[][] b)
  {
    int[][] c = new int [a.length][b[0].length];

    for (int i = 0; i < c.length; i++)
    {
       for (int j = 0; j < c[i].length; j++)
       {
         int sum = 0;
         for (int k = 0; k < b.length; k++)
	 {
           sum += a[i][k] * b[k][j];
	 }

	 c[i][j] = sum;
       }
    }
    return c;
  }


  public static int max (int[][] a)
  {
    int maxVal = a[0][0];
    for (int i = 0; i < a.length; i++)
    {
      for (int j = 0; j < a[i].length; j++)
      {
        if (a[i][j] > maxVal)
	  maxVal = a[i][j];
      }
    }
    return maxVal;
  }

  public static void main (String[] args)
  {

  }
}