/*
*-----------------------------------------------------------------------------
* funct: mat_minor
* desct: find minor
* given: A = a square matrix,
* i=row, j=col
* retrn: the minor of Aij
*-----------------------------------------------------------------------------
*/
double mat_minor(MATRIX A,int i,int j)
{
MATRIX S;
double result;
if ( ( S = mat_creat(MatRow(A)-1, MatCol(A)-1, UNDEFINED) ) == NULL )
return -1.0;
mat_submat(A, i, j, S);
result = mat_det( S );
mat_free(S);
return (result);
}
//---------------------------------------------------------------------------
// Compute determinant of the matrix
NaReal NaMatrix::det () const
{
#ifdef __matrix_h
if(dim_rows() != dim_cols()){
throw(na_size_mismatch);
}
NaReal vDet = 0;
MATRIX mat = mat_creat(dim_rows(), dim_cols(), UNDEFINED);
unsigned i, j, n = dim_rows();
for(i = 0; i < n; ++i){
for(j = 0; j < n; ++j){
mat[i][j] = get(i, j);
}
}
vDet = mat_det(mat);
mat_free(mat);
return vDet;
#else
throw(na_not_implemented);
#endif/* __matrix_h */
#if 0
unsigned i, j, k, n = dim_rows();
// Predefined det()
switch(n){
case 1:
vDet = get(0, 0);
break;
case 2:
vDet = get(0, 0) * get (1, 1) - get(0, 1) * get(1, 0);
break;
default:{
// Allocate space for minor matrix
NaMatrix mOfMinor(n - 1, n - 1);
for(i = 0; i < n; ++i){
// Compose minor
for(j = 0; j < n - 1; ++j){
for(k = 0; k < n - 1; ++k){
if(k < i){
mOfMinor[j][k] = get(1 + j, k);
}else if(k >= i){
mOfMinor[j][k] = get(1 + j, 1 + k);
}
}
}// minor composition
//NaPrintLog("Minor(%d,%d):\n", i, n - 1);
//mOfMinor.print_contents();
// Summarize determinant
if(i % 2){
vDet -= get(0, i) * mOfMinor.det();
}else{
vDet += get(0, i) * mOfMinor.det();
}
}
}break;
}// end of switch for different cases
//NaPrintLog("det=%g\n", vDet);
return vDet;
#endif
}
