double matrix_determinant(Matrix M)
{
assert(is_square_matrix(M));
double temp;
double det = 1;
int n = M->c;
if(n == 2) {
return M->A[0][0] * M->A[1][1] - M->A[1][0] * M->A[0][1];
}
Matrix A = matrix_copy(M);
for (int k = 0; k < n; k++) {
int j = k;
double max = A->A[j][j];
for (int i = k + 1; i < n; i++)
if ((temp = fabs(A->A[i][k])) > max) {
j = i;
max = temp;
}
matrix_swap_row(A, NULL, k, j);
if(k != j)
det *= -1;
for (int i = k + 1; i < n; i++) {
temp = A->A[i][k] / A->A[k][k];
for (int j = k + 1; j < n; j++)
A->A[i][j] -= temp * A->A[k][j];
A->A[i][k] = 0;
}
}
assert(is_square_matrix(A));
for(int i = 0; i < n; i++)
det *= A->A[i][i];
free(A);
return det;
}
Matrix matrix_inverse(Matrix M)
{
if(!is_square_matrix(M))
return NULL;
int n = M->r;
Matrix N = matrix_new_empty(n, n);
double det = matrix_determinant(M);
if(double_equals(det, 0))
return NULL;
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++) {
Matrix C = matrix_cofactor(M, i, j);
if((i + j) % 2 == 0)
N->A[i][j] = matrix_determinant(C) / det;
else
N->A[i][j] = -1 * matrix_determinant(C) / det;
matrix_free(C);
}
Matrix I = matrix_transpose(N);
matrix_free(N);
assert(is_square_matrix(I));
return I;
}
void _main(void)
{
short i_menu_choice;
graph *p_graph = NULL;
matrix *p_matrix = NULL;
point v_key[8];
ESI EsiPtr = top_estack; //pointer en haut de la pile
FontSetSys(F_6x8);
clrscr();
//Verifie si une matrice est passée en parametre
if((GetArgType(EsiPtr) != LIST_TAG)||(GetArgType(EsiPtr-1) != LIST_TAG)){ //Ce n'est pas une matrice
EsiPtr = open_file(); //Si ce n'est pas la cas, ouvrir une fenetre
}
//sym = DerefSym(SymFind(GetSymstrArg(EsiPtr)));
if(! is_square_matrix(EsiPtr)){
printf("\Error : The matrix must be a squared matrix (same height and width). ");
ngetchx();
exit(0);
}