C > Beginners Lab Assignments

Program to Multiply Two Matrices

Program to Multiply Two Matrices

#define MAXROWS 30
#define MAXCOLS 30
void readinput(int a[][MAXCOLS],int m,int n);
void computeproduct(int a[][MAXCOLS],int b[][MAXCOLS],int c[][MAXCOLS],int m,int n,int p);
void writeoutput(int c[][MAXCOLS],int m,int p);
int z=0;
void main()
{

 /* char c;*/
 int nrows,ncols,mrows,mcols;
 int a[MAXROWS][MAXCOLS],b[MAXROWS][MAXCOLS],c[MAXROWS][MAXCOLS];
 clrscr();
 printf("

How many rows in the first matrix?  ");
 scanf("%d",&nrows);
 printf("

How many cols in the first matrix?  ");
 scanf("%d",&ncols);
 printf("

How many rows in the second matrix?  ");
 scanf("%d",&mrows);
 printf("

How many cols in the second matrix?  ");
 scanf("%d",&mcols);
 if (ncols != mrows)
 {
  printf("The product of these matrices is not defined.");
  getch();
  exit(0);
 }
 printf("

First table:
");
 readinput(a,nrows,ncols);
 printf("

Second table:
");
 readinput(b,mrows,mcols);

 computeproduct(a,b,c,nrows,ncols,mcols);

 printf("

Product of the matrices is:

");
 writeoutput(c,nrows,mcols);

 getch();
}


void readinput(int a[][MAXCOLS],int m,int n)
{
 int row,col;
 for (row=0;row<m;row++)
 {
  printf("
Enter data for row no. %4d
",row+1);
  for (col=0;col<n;col++)
   scanf("%d",&a[row][col]);
 }
 z=z+1;
 printf("	Table %d
",z);
 for (row=0;row<m;row++)
 {
  for (col=0;col<n;col++)
   printf("%d%c",a[row][col],' ');
  printf("
");
 }
 return;
}


void computeproduct(int a[][MAXCOLS],int b[][MAXCOLS],int c[][MAXCOLS],int m,int n,int p)
{
 int i,j,k,sum=0;
 for (i=0;i<m;i++)
 {
  for (j=0;j<p;j++)
  {
   for (k=0;k<n;k++)
	sum=sum+(a[i][k]*b[k][j]);
   c[i][j]=sum;
   sum=0;
  }
 }
 return;
}


void writeoutput(int c[][MAXCOLS],int m,int p)
{
 int row,col;
 for (row=0;row<m;row++)
 {
  for (col=0;col<p;col++)
   printf("%6d",c[row][col]);
  printf("
");
 }
 return;
}