#include<stdio.h>
#include<math.h>
float detrminant(float[][], float);
void cofactors(float[][], float);
void trans(float[][], float[][], float);
void main()
{
float a[25][25], n, d;
int i, j;
printf("Enter the order of the matrix:\n");
scanf("%f", &n);
printf("Enter the elemnts into the matrix:\n");
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
scanf("%f", &a[i][j]);
}
}
d = detrminant(a, n);
printf("\nTHE DETERMINANT IS=%2f", d);
if (d == 0)
printf("\nMATRIX IS NOT INVERSIBLE\n"); else
cofactors(a, n);
}
float detrminant(float a[25][25], float k) {
float s = 1, det = 0, b[25][25];
int i, j, m, n, c;
if (k == 1) {
return (a[0][0]);
}
else
{
det = 0;
for (c = 0; c < k; c++)
{
m = 0;
n = 0;
for (i = 0; i < k; i++) {
for (j = 0; j < k; j++) {
b[i][j] = 0;
if (i != 0 && j != c) {
b[m][n] = a[i][j];
if (n < (k - 2))
n++; else {
n = 0;
m++;
}
}
}
}
det = det + s * (a[0][c] * detrminant(b, k - 1));
s = -1 * s;
}
}
return (det);
}
void cofactors(float num[25][25], float f) {
float b[25][25], fac[25][25];
int p, q, m, n, i, j;
for (q = 0; q < f; q++) {
for (p = 0; p < f; p++) {
m = 0;
n = 0;
for (i = 0; i < f; i++) {
for (j = 0; j < f; j++) {
b[i][j] = 0;
if (i != q && j != p) {
b[m][n] = num[i][j];
if (n < (f - 2)
n++; else {
n = 0;
m++;
}
}
}
}
fac[q][p] = pow(-1, q + p) * detrminant(b, f - 1);
}
}
trans(num, fac, f);
}
void trans(float num[25][25], float fac[25][25], float r) {
int i, j;
float b[25][25], inv[25][25], d;
for (i = 0; i < r; i++) {
for (j = 0; j < r; j++) {
b[i][j] = fac[j][i];
}
}
d = detrminant(num, r);
inv[i][j] = 0;
for (i = 0; i < r; i++) {
for (j = 0; j < r; j++) {
inv[i][j] = b[i][j] / d;
}
}
printf("\nTHE INVERSE OF THE MATRIX:\n");
for (i = 0; i < r; i++) {
for (j = 0; j < r; j++) {
printf("\t%2f", inv[i][j]);
}
printf("\n");
}
}
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