/*
* @function polynomial_remove_null_monomials
*
* Remove all monomials from polynomial where coefficient is 0
*/
static void polynomial_remove_null_monomials(Polynomial *polynomial) {
assert(polynomial != NULL);
Monomial *current = polynomial->first, *previous = NULL;
while(current != NULL) {
double coefficient = monomial_get_coefficient(current);
if(is_coefficient_null(coefficient)) {
// remove this monomial
if(current == polynomial->first) {
polynomial->first = monomial_get_next(current);
monomial_free(¤t);
current = polynomial->first;
} else {
Monomial *next = monomial_get_next(current);
monomial_free(¤t);
current = next;
monomial_set_next(previous, current);
}
continue;
}
previous = current;
current = monomial_get_next(current);
}
polynomial_recalculate_degree(polynomial);
}
Polynomial* polynomial_product(const Polynomial* leftp, const Polynomial* rightp) {
assert(leftp != NULL);
assert(rightp != NULL);
/*
* Steps for the product of two polynomials:
* - compute the degree of the product
* - create an array to store the product
* - compute the product by adding the product of each monomial in leftp with each monomial in rightp to the array
* - convert the array back to a polynomial
*/
// compute the degree of the product
long result_degree = leftp->degree + rightp->degree;
// create an array to store the product
double *result_coefficients = malloc(sizeof(double) * (result_degree + 1));
if(!result_coefficients) {
fprintf(stderr, "Fatal error: couldn't allocate %zu bytes!\nExiting\n", sizeof(double) * (result_degree + 1));
exit(EXIT_FAILURE);
}
int index_coefficient = 0;
for(; index_coefficient < result_degree + 1; index_coefficient++) {
result_coefficients[index_coefficient] = 0;
}
// compute the product by adding the product of each monomial in leftp with each monomial in rightp to the array
Monomial *current = leftp->first;
while(current != NULL) {
Monomial *rightm = rightp->first;
while(rightm != NULL) {
Monomial *productm = monomial_product(current, rightm);
long productm_degree = monomial_get_degree(productm);
double productm_coefficient = monomial_get_coefficient(productm);
result_coefficients[productm_degree] += productm_coefficient;
monomial_free(&productm);
rightm = monomial_get_next(rightm);
}
current = monomial_get_next(current);
}
Polynomial *product = polynomial_create(result_coefficients, result_degree);
polynomial_remove_null_monomials(product);
free(result_coefficients);
return product;
}
void polynomial_free(Polynomial** polynomial) {
assert(polynomial != NULL);
assert(*polynomial != NULL);
Monomial* current = (*polynomial)->first, *next = NULL;
while(current != NULL) {
next = monomial_get_next(current);
monomial_free(¤t);
current = next;
}
free(*polynomial);
*polynomial = NULL;
}
void polynomial_remove(polynomial_t *p, unsigned long degree)
{
monomial_t *current = NULL, *tmp = NULL;
// Mesure de sécurité
if (p == NULL)
return;
// On parcourt le polynôme jusqu'au monôme à supprimer
current = p->first;
while (current != NULL && current->degree != degree)
current = current->next;
// Si on n'a pas trouvé le monôme, on arrête
if (current == NULL)
return;
// On retire le monôme du polynôme
if (current->previous != NULL)
current->previous->next = current->next;
else
p->first = current->next;
if (current->next != NULL)
current->next->previous = current->previous;
else
p->last = current->previous;
// Si c'était le monôme de plus grand degré
if (p->degree == current->degree)
{
// On doit retrouver le nouveau degré du polynôme (par défaut, il vaut 0)
tmp = p->first;
p->degree = 0;
while (tmp != NULL)
{
if (tmp != current && tmp->degree > p->degree)
p->degree = tmp->degree;
}
}
// On libère le monôme de la mémoire et on décrémente la taille du polynôme
monomial_free(current);
p->size--;
}
void polynomial_free(polynomial_t *p)
{
monomial_t *m = NULL, *tmp = NULL;
// Petite mesure de sécurité
if (p == NULL)
return;
// On libère de la mémoire tous les monômes du polynôme
m = p->first;
while (m != NULL)
{
tmp = m->next;
monomial_free(m);
m = tmp;
}
// Et on libère le reste de la mémoire
free(p->name);
free(p);
}
void polynomial_insert(polynomial_t *p, monomial_t *m)
{
monomial_t *current = NULL;
complex_t *tmp = NULL;
// Mesure de sécurité
if (p == NULL || m == NULL)
return;
// On parcourt la liste jusqu'à ce que la puissance de monôme ne soit plus inférieure
current = p->first;
while (current != NULL && m->degree < current->degree)
current = current->next;
// S'il n'y a pas d'éléments dans la liste
if (current == NULL && p->first == NULL && p->last == NULL)
{
// On définit le monôme comme le premier et dernier élément du polynôme
p->first = m;
p->last = m;
p->degree = m->degree;
p->size++;
}
else if (current == NULL) // Si on se trouve à la fin du polynôme
{
// On définit la nouvelle fin du polynôme
m->previous = p->last;
m->previous->next = m;
p->last = m;
p->size++;
}
else if (current->degree == m->degree) // Si on est dans le polynôme et que le monôme courant à le même degré
{
// On fait la somme des facteurs
tmp = complex_sum(current->coef, m->coef);
if (tmp == NULL)
return;
complex_free(current->coef);
current->coef = tmp;
// Si notre monôme a un coefficient nul
if (current->coef->mod == 0.0)
polynomial_remove(p, current->degree);
// Et on libère le monôme à insérer pour n'en garder qu'un
monomial_free(m);
}
else // Sinon
{
// On place le monôme dans le polynôme
m->previous = current->previous;
m->next = current;
// On règle les liens ascendant et descendant du monôme
current->previous = m;
if (m->previous != NULL)
m->previous->next = m;
else
p->first = m;
// Si le monôme inséré a le plus grand degré
if (m->degree > p->degree)
p->degree = m->degree;
p->size++;
}
}
