#### Gauss Elimination

```#include <math.h>
#include <stdio.h>

#define ARRAY_SIZE 20

void display(float a[ARRAY_SIZE][ARRAY_SIZE], int n)
{
int i, j;
for (i = 0; i < n; i++)
{
for (j = 0; j <= n; j++)
{
printf("%.2f \t", a[i][j]);
}
printf("\n");
}
}

float interchange(float m[ARRAY_SIZE][ARRAY_SIZE], int i, int n)
{
float tmp[ARRAY_SIZE][ARRAY_SIZE];
float max = fabs(m[i][i]);
int j, k = i;

for (j = i; j < n; j++)
{
if (max < fabs(m[j][i]))
{
max = fabs(m[j][i]);
k = j;
}
}
for (j = 0; j <= n; j++)
{
tmp[i][j] = m[i][j];
m[i][j] = m[k][j];
m[k][j] = tmp[i][j];
}
return m[ARRAY_SIZE - 1][ARRAY_SIZE - 1];
}
float eliminate(float m[ARRAY_SIZE][ARRAY_SIZE], int i, int n)
{
float tmp;
int k = 1, l, j;
for (j = i; j < n - 1; j++)
{
tmp = -((m[i + k][i]) / (m[i][i]));
for (l = 0; l <= n; l++)
{
m[i + k][l] = (m[i + k][l]) + (m[i][l] * tmp);
}
k++;
}
return m[ARRAY_SIZE - 1][ARRAY_SIZE - 1];
}
int main(void)
{
int i, j, n, k = 0, l;
float m[ARRAY_SIZE][ARRAY_SIZE], mul, tmp[ARRAY_SIZE][ARRAY_SIZE], val,
ans[ARRAY_SIZE];

printf("Total No.of Equations : ");
scanf("%d", &n);

printf("\n");
for (i = 0; i < n; i++)
{
printf("Enter Co-efficient Of Equations %d & Total --->>>\n", i + 1);
for (j = 0; j <= n; j++)
{
printf("r%d%d : ", i, j);
scanf("%f", &m[i][j]);
}
printf("\n");
}
printf(":::::::::::: Current Matrix ::::::::::::\n\n");
display(m, n);

for (i = 0; i < n - 1; i++)
{
printf("\n------->>>>>>>>>>>>>>>>>>>>>>>>-------- %d\n", i + 1);
m[ARRAY_SIZE - 1][ARRAY_SIZE - 1] = interchange(m, i, n);
display(m, n);
printf("\n_______________________________________\n");
m[ARRAY_SIZE - 1][ARRAY_SIZE - 1] = eliminate(m, i, n);
display(m, n);
}
printf("\n\n Values are : \n");
for (i = n - 1; i >= 0; i--)
{
l = n - 1;
mul = 0;
for (j = 0; j < k; j++)
{
mul = mul + m[i][l] * ans[l];
l--;
}
k++;
ans[i] = (m[i][n] - mul) / m[i][i];
printf("X%d = %.2f\n", i + 1, ans[i]);
}

return 0;
}
```