C code to solve Laplace's Equation by finite difference method

/*******************************************************************************/

/*************Program to solve Laplace's equation by finite difference method*************/

/*************************** Developed by Mahesha M G ***************************/

#include <stdio.h>

main()

{

int i,j,k,m,n,x,y;

float a[20][20],l,r,t,b;

FILE *fp;

clrscr();

fp=fopen("c:\\laplace.dat","w"); //output will be stored in this file

printf("\t_______________________________________________________________\n");

printf("\tProgram to solve Laplace's equation by finite difference method\n");

printf("\t****************** Developed by Mahesha M G *******************\n");

printf("\t_______________________________________________________________\n");

printf("\tEnter boundary conditions\n");

printf("\tValue on left side: ");

scanf("%f",&l);

printf("\tValue on right side: ");

scanf("%f",&r);

printf("\tValue on top side: ");

scanf("%f",&t);

printf("\tValue on bottom side: ");

scanf("%f",&b);

printf("\tEnter length in x direction: ");

scanf("%d",&x);

printf("\tEnter number of steps in x direction: ");

scanf("%d",&m);

printf("\tEnter length in y direction: ");

scanf("%d",&y);

printf("\tEnter number of steps in y direction: ");

scanf("%d",&n);

m++;

n++; //number of mesh points is one more than number of steps

            for(i=1;i<=m;i++)   //assigning boundary values begins

            {

              a[i][1]=b;

              a[i][n]=t;

            }

            for(i=1;i<=n;i++)

            {

              a[1][i]=l;

              a[m][i]=r;

            }                         //assigning boundary values ends

for(i=2;i<m;i++)

for(j=2;j<n;j++)

a[i][j]=t; //initialization of interior grid points 

for(k=0;k<100;k++)

  {

               for(i=2;i<m;i++)

            {

               for(j=2;j<n;j++)

               {

                a[i][j]=(a[i-1][j]+a[i+1][j]+a[i][j-1]+a[i][j+1])/4;

               }

            }

   }                     //calculation by Gauss-Seidel Method

            for(i=1;i<=m;i++)

            {

               for(j=1;j<=n;j++)

               fprintf(fp,"%.2f\t",a[i][j]);

            fprintf(fp,"\n");

            }

  fclose(fp);

  printf("\nData stored\nPress any key to exit...");

             getch();

}

SAMPLE INPUT 

PLOT OF DATA GENERATED BY C PROGRAM