void matrix_to_entity(MATRIX *m) {
int depth, cur, maxdepth = MIN(m->cols, m->rows) ;
for(depth = 0; depth < maxdepth; depth++) {
for (cur = depth+1; cur < maxdepth; cur++) {
FRAC *piv = matrix_get_val(m, depth, depth) ;
FRAC *tz = matrix_get_val(m, cur, depth) ;
FRAC fac ;
if(tz->num != 0) {
frac_div(&fac, piv, tz) ;
frac_negate(&fac, &fac) ;
matrix_multiply_row(m, cur, &fac) ;
matrix_add_row(m, cur, depth) ;
}
}
}
for(depth = maxdepth - 1; depth >= 0; depth--) {
for (cur = depth-1; cur >= 0; cur--) {
FRAC *piv = matrix_get_val(m, depth, depth) ;
FRAC *tz = matrix_get_val(m, cur, depth) ;
FRAC fac ;
if(tz->num != 0) {
frac_div(&fac, piv, tz) ;
frac_negate(&fac, &fac) ;
matrix_multiply_row(m, cur, &fac) ;
matrix_add_row(m, cur, depth) ;
}
}
}
for(depth = 0; depth < maxdepth; depth++) {
FRAC t, *e = matrix_get_val(m, depth, depth) ;
if (e->num != 0) {
frac_inverse(&t,e) ;
matrix_multiply_row(m, depth, &t) ;
}
}
}
FRACTION frac_subtract(FRACTION lhs, FRACTION rhs)
{
return frac_add(lhs, frac_negate(rhs));
}
