Stage One Define the specification of the program
 
         Add two nxm size matrices
 
Stage Two Divide the program up into separate modules
 
        Input Matrix
        Add Matrix
        Display Matrix

Stage Four Develop the Algorithm
 
    Title: Matin
  
    Input: Matrix array, size, name
 
    Output: Matrix array
 
    Function:  Load up array from standard input/output
 
    Title: Matadd
  
    Input: Matrix array1, Matrix Array2, size , 
 
    Output: Matrix array3
 
    Function:  Matrix Array3 = Matrix Array2 + Matrix Array1
 
 
    Title: Matout
  
    Input: Matrix array, size, 
 
    Output: none
 
    Function:  Display an array using standard input/output 

Stage Five Code each module and write a main program to combine all the code.
 
    Title: Matin
  
    Input: Matrix array, size , 
 
    Output: Matrix array
 
 
    Function:  Load up array from standard input/output
 
 
Before we code these modules we need to look at passing arrays in and out of functions. Here we must introduce the concept of the address of a variable. Within micros each variable is stored in memory at an address i.e. house number. If we  pass across the actual address to a function and use that address to store data , then upon the return of the function , we have automatically return the required data , without using the return statement . This is termed 'return by address' and is how can works i.e.
 
    scanf("%f",&value);
 
Here the function returns back the figure into the variable value, the '&' means pass across the address not the actual value. Simply to use arrays in functions we must pass the address across else we must use the return command.
 
void  matin (int n, int m ,char name,float a[11][11])
{  
  /* Author: Mr James Mc Carren */
  /* Company: Staffordshire University */
  /*Date: 26th August 2012 */
  /*Version 1.0 */
/*Function: Procedure to input a nxm matrix using standard input

Parameters used:   n,m size of matrix Name Character to identify Which matrix is loaded Temp of type d which is an two dimensional array  
Modifications:   none */
  int i,j;      
/*Load up matrix A*/
  for (j=1;j<=n;j++)
      {
       for (i=1;i<=m;i++)
          {
     printf(" Please enter element %3d %3d ", j ,i);
    printf("of matrix %c\n\r",name);
      scanf("%f",&a[j][ i]);
          }
      }
  return;
}

    Title: Matadd
    Input: Matrix array1, Matrix Array2 , size ,  
    Output: Matrix array3
    Function:  Matrix Array3 = Matrix Array2 + Matrix Array1
 
void matadd (int n,int  m,float a[11][11],float b[11][11],float c[11][11])
{
 
 /*Author: Mr James Mc Carren 
 Company: Staffordshire University 
 Date: 26th August 2012 
 Version 1.0 
Function: Procedure to add two nxm matrixes using standard input

Parameters used: n,m  integer values  matrix size Array A and B of type d  Array C used as output Name Character to identify Which matrix is loaded  Type d which is an two dimensional array          

Modifications:   none*/
 
  int i,j;  
  /*Add matrix A to B to make C i.e [C] = [A] + [B]*/
     for (j=1;j<=n;j++)
    {
        for (i=1;i<=m;i++)
            {
      c[j][ i] = a[j][ i] + b[j][ i];
            }
        }
  return;
}
     
    Title: Matout  
    Input: Matrix array, size , 
    Output: none
    Function:  Display an array using standard input/output
 
void matout (int n, int m, char name, float c[11][11] )
{
 /*Author: Mr James Mc Carren 
Company: Staffordshire University 
 Date: 26th August 2012 
Version 1.0 
Function: Procedure to input an nxm matrix using standard input

Parameters used: n,m size of matrix Temp of type d which is an two dimensional array       
Modifications:   none*/
  int i,j;  
  /*Display matrix C*/
    for (j=1;j<=n;j++)
        {
        for (i=1;i<=m;i++)
            {
       printf("Element %3d %3d ", j , i );
       printf("of matrix %c is %10.2f \n\r",name, c[j][ i]);
            }
        }
  }