C Program for Matrix Multiplication

This is a c program for Matrix Multiplication. To understand how it works, you should first know how matrix multiplication is done mathematically.

#include <stdio.h>
void main()
{
int m1[10][10],i,j,k,m2[10][10],prod[10][10],r1,c1,r2,c2;
printf("Enter number of rows and columns of first matrix:\n");
scanf("%d%d",&r1,&c1);
printf("Enter number of rows and columns of second matrix:\n");
scanf("%d%d",&r2,&c2);
if(r2==c1)
    {
    printf("Enter elements of First matrix (row wise):\n");
    for(i=0;i<r1;i++)
        for(j=0;j<c1;j++)
            scanf("%d",&m1[i][j]);
    printf("Matrix1 is :\n");
    for(i=0;i<r1;i++)
        {
        for(j=0;j<c1;j++)
            printf("%d ",m1[i][j]);
        printf("\n");
        }
    printf("Enter elements of Second matrix (row wise):\n");
    for(i=0;i<r2;i++)
        for(j=0;j<c2;j++)
            scanf("%d",&m2[i][j]);
    printf("Matrix2 is:\n");
    for(i=0;i<r2;i++)
        {
        for(j=0;j<c2;j++)
            printf("%d ",m2[i][j]);
        printf("\n");
        }
    printf("Product of the Matrices (M1 x M2):\n");
    for(i=0;i<r1;i++)
        {
        for(j=0;j<c2;j++)
            {
            prod[i][j]=0;
            for(k=0;k<r1;k++)
                prod[i][j]+=m1[i][k]*m2[k][j];
            printf("%d\ ",prod[i][j]);
            }
        printf("\n");
        }
    }
else
    {
    printf("Matrices can't be multiplied.\n");
    printf("No. of columns of first matrix and no of rows of second are different.");
    }
}

C Program To Represent Directed or Undirected Graph Using Adjacency Matrix

C program to represent directed or undirected graph using Adjacency matrix.

#include<stdio.h>
#include<conio.h>
#define max 20
int adj[max][max]; //Adjacency matrix
int n;  //Denotes number of nodes in the graph
void main()
 {

  int max_edges,i,j,origin,destin;
  char graph_type;
  printf("Enter number of nodes : ");
  scanf("%d",&n);
  printf("Enter type of graph, directed or undirected.\n");
   printf("Enter d for directed and u for undirected:\n ");
  fflush(stdin);
   scanf("%c",&graph_type);
   if(graph_type=='u')
    max_edges=n*(n-1)/2;
  else
    max_edges=n*(n-1);
  for(i=1;i<=max_edges;i++)
    {
    printf("Enter edge %d( 0 0 to quit ) : ",i);
    scanf("%d %d",&origin,&destin);
    if( (origin==0) && (destin==0) )
     break;
    if( origin > n || destin > n || origin<=0 || destin<=0)
     {
     printf("Invalid edge!\n");
     i--;
     }
    else
     {
     adj[origin][destin]=1;
     if( graph_type=='u')
      adj[destin][origin]=1;
     }
    }

  printf("The adjacency matrix is :\n");
  for(i=1;i<=n;i++)
    {
    for(j=1;j<=n;j++)
     printf("%4d",adj[i][j]);
    printf("\n");
    }
   getch();
  }

C Program to Sort a Matrix Column wise using Pointers

This is a c program to sort a mxn matrix column wise in ascending order using pointers. To sort column wise in descending order, just replace the '>' symbol in the comparing line of code into '<'. That part of the code is marked with a comment 'comparison'.

#include<stdio.h>
main()
{
int a[7][7],i,j,k,m,n,temp;

//reading
printf("enter number of rows of matrix\n");
scanf("%i",&m);
printf("enter number of columns of matrix\n");
scanf("%i",&n);
printf("enter the elements\n");
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
scanf("%d",&a[i][j]);
}
//displaying
printf("the matrix you entered:\n");
for(i=0;i<m;i++)
{
printf("\n");
for(j=0;j<n;j++)
{
printf("%4d",*(*(a+i)+j));
}
}


//sorting
for(i=0;i<n;i++)
{
for(k=0;k<m-1;k++)
{
for(j=0;j<m-k-1;j++)
{
//comparison
if( *(*(a+j)+i)> *(*(a+(j+1))+i)) 
{
temp=*(*(a+j)+i);
*(*(a+j)+i)=*(*(a+(j+1))+i);
*(*(a+(j+1))+i)=temp;
}
}
}
}
//displaying
printf("\nSorted Matrix:\n");
for(i=0;i<m;i++)
{
printf("\n");
for(j=0;j<n;j++)
{
printf("%4d",*(*(a+i)+j));
}
}
}

Determinant of Matrix Program - Program to Find Determinant of Matrix

In this post i am sharing a C program to calculate determinant of matrices. Determinant exists only for square matrix. Here i have wrote a c program to find determinant of matrices of order less than or equal to 3.

#include<stdio.h>

void main()
{
int a[10][10],i,m,j;
int det=0;
printf("\nEnter the order of matrix:\n ");
scanf("%i",&m);
printf("\nenter elements\n");
for(i=0;i<m;i++)
 {
 for(j=0;j<m;j++)
  scanf("%d",&a[i][j]);
 }
printf("\nThe matrix is\n");
for(i=0;i<m;i++)
 {
 printf("\n");
 for(j=0;j<m;j++)
  printf("%3d",a[i][j]);
 }
printf("\nthe transpose is\n");
for(i=0;i<m;i++)
{
for(j=0;j<m;j++)
printf("%3i",a[j][i]);
printf("\n");
}
if(m==1)
{
det=a[0][0];
printf("det=%i",det);
}
else if(m==2)
{
int k=1,l=1;
for(i=0;i<2;i++)
for(j=0;j<2;j++)
{
if(i==j)
k*=a[i][j];
else
l*=a[i][j];
}
printf("\ndeterminant=%i",k-l);
}
else if(m==3)
{
for(i=0;i<3;i++)
det=det+(a[0][i]*(a[1][(i+1)%3]*a[2][(i+2)%3]-a[1][(i+2)%3]*a[2][(i+1)%3])); 
printf("\nDeterminant of matrix is: %d",det);
}
else
printf("This program can't calculate determinant of matrix of order greater than 3");
}