Here's a C program for solving simultaneous equation using Gauss elimination method using for loops with output. This program uses Array, For Loops and Nested Loops.
Output of above program is
Enter the number of equations : 3
Enter the co-efficients of the equations :
a[1][1] = 10
a[1][2] = 1
a[1][3] = 1
b[1] = 12
a[2][1] = 2
a[2][2] = 10
a[2][3] = 1
b[2] = 13
a[3][1] = 1
a[3][2] = 1
a[3][3] = 5
b[3] = 7
The result is :
x[1] = 1.00
x[2] = 1.00
x[3] = 1.00
# include <stdio.h>
# include <conio.h>
void main()
{
int i, j, k, n ;
float a[20][20], x[20] ;
double s, p ;
clrscr() ;
printf("Enter the number of equations : ") ;
scanf("%d", &n) ;
printf("\nEnter the co-efficients of the equations :\n\n") ;
for(i = 0 ; i < n ; i++)
{
for(j = 0 ; j < n ; j++)
{
printf("a[%d][%d] = ", i + 1, j + 1) ;
scanf("%f", &a[i][j]) ;
}
printf("b[%d] = ", i + 1) ;
scanf("%f", &a[i][n]) ;
}
for(k = 0 ; k < n - 1 ; k++)
{
for(i = k + 1 ; i < n ; i++)
{
p = a[i][k] / a[k][k] ;
for(j = k ; j < n + 1 ; j++)
a[i][j] = a[i][j] - p * a[k][j] ;
}
}
x[n-1] = a[n-1][n] / a[n-1][n-1] ;
for(i = n - 2 ; i >= 0 ; i--)
{
s = 0 ;
for(j = i + 1 ; j < n ; j++)
{
s += (a[i][j] * x[j]) ;
x[i] = (a[i][n] - s) / a[i][i] ;
}
}
printf("\nThe result is :\n") ;
for(i = 0 ; i < n ; i++)
printf("\nx[%d] = %.2f", i + 1, x[i]) ;
getch() ;
}
Output of above program is
Enter the number of equations : 3
Enter the co-efficients of the equations :
a[1][1] = 10
a[1][2] = 1
a[1][3] = 1
b[1] = 12
a[2][1] = 2
a[2][2] = 10
a[2][3] = 1
b[2] = 13
a[3][1] = 1
a[3][2] = 1
a[3][3] = 5
b[3] = 7
The result is :
x[1] = 1.00
x[2] = 1.00
x[3] = 1.00
