static gsl_poly_int* mygsl_poly_hermite(int n1)
{
size_t n;
gsl_vector_int *p1, *p2, *p0;
int coef1[2] = {0, 2};
int coef2[3] = {-2, 0, 4};
if (n1 < 0) rb_raise(rb_eArgError, "order must be >= 0");
p0 = gsl_vector_int_calloc(n1 + 1);
switch (n1) {
case 0:
gsl_vector_int_set(p0, 0, 1);
break;
case 1:
memcpy(p0->data, coef1, 2*sizeof(int));
break;
case 2:
memcpy(p0->data, coef2, 3*sizeof(int));
break;
default:
p1 = gsl_vector_int_calloc(n1 + 1);
p2 = gsl_vector_int_calloc(n1 + 1);
memcpy(p1->data, coef2, 3*sizeof(int));
memcpy(p2->data, coef1, 2*sizeof(int));
for (n = 2; n < n1; n++) {
gsl_vector_int_memcpy(p0, p1);
mygsl_vector_int_shift_scale2(p0, n);
gsl_vector_int_scale(p2, 2*n);
gsl_vector_int_sub(p0, p2);
/* save for the next iteration */
gsl_vector_int_memcpy(p2, p1);
gsl_vector_int_memcpy(p1, p0);
}
gsl_vector_int_free(p2);
gsl_vector_int_free(p1);
break;
}
return p0;
}
static VALUE rb_gsl_vector_int_sub(VALUE obj, VALUE b)
{
gsl_vector_int *v, *vnew, *vb;
switch (TYPE(b)) {
case T_FIXNUM:
return rb_gsl_vector_int_add_constant(obj, INT2FIX(-FIX2INT(b)));
break;
case T_FLOAT:
return rb_gsl_vector_add_constant(rb_gsl_vector_int_to_f(obj), rb_float_new(-NUM2DBL(b)));
break;
default:
if (rb_obj_is_kind_of(b, cgsl_vector_int)) {
Data_Get_Struct(obj, gsl_vector_int, v);
Data_Get_Struct(b, gsl_vector_int, vb);
vnew = gsl_vector_int_alloc(v->size);
gsl_vector_int_memcpy(vnew, v);
gsl_vector_int_sub(vnew, vb);
return Data_Wrap_Struct(VECTOR_INT_ROW_COL(obj), 0, gsl_vector_int_free, vnew);
} else {
return rb_gsl_vector_sub(rb_gsl_vector_int_to_f(obj), b);
}
break;
}
}
