double MATHNS::angle(std::vector<double> u, std::vector<double> v)
{
double um = vector_mag(u);
double vm = vector_mag(v);
double dot = vector_dot(u,v);
return acos(dot/(um*vm));
}
void test_vector_magnitudes() {
printf("Testing vector magnitudes...\n");
TestStats stats = test_stats();
Vector test_vector;
double computed;
test_vector = zeroes(0);
computed = vector_mag(&test_vector);
assert_double(&stats, 0, computed,
"Zero element vectors should have zero magnitude");
int i;
for (i = -1; i < 3; i++) {
test_vector = linear(1, i, 0);
computed = vector_mag(&test_vector);
assert_double(&stats, abs(i), computed,
"One element vectors must have magnitude equal to their element.");
}
double quad_a[4] = {-.4, 0, .6, 1.2};
Vector quad = { 4, &quad_a[0] };
computed = vector_mag(&quad);
assert_double(&stats, 1.4, computed,
"Incorrectly computed vector magnitude");
print_state(&stats);
}
static void compute_normal(point_t* points, int num_points, vector_t* n)
{
vector_t A, B;
point_displacement(&points[0], &points[1], &A);
point_displacement(&points[0], &points[2], &B);
vector_cross(&A, &B, n);
ASSERT(vector_mag(n) > 0.0);
vector_normalize(n);
}
Vector gravitational_acel (Body a, Body b) {
Vector res;
double force, tmp;
force = G * b->bbody.mass;
res = vector_zeros (a->bbody.position->size);
vector_copy (res, a->bbody.position);
vector_sub (res, b->bbody.position);
tmp = vector_mag (res);
if (tmp == 0) {
fprintf (stderr, "gravitational_force: ");
fprintf (stderr, "Division by zero.\n");
/* exit(EXIT_FAILURE); */
tmp = 0.00001;
}
force /= tmp*tmp*tmp;
vector_scale (res, force);
return res;
}
static vector_t hat_grad(void* context, vector_t* y)
{
real_t h = *((real_t*)context); // Spatial extent of W.
real_t D = vector_mag(y);
static vector_t zero = {.x = 0.0, .y = 0.0, .z = 0.0};
vector_t g = {.x = -y->x/(D*h), .y = -y->y/(D*h), .z = -y->z/(D*h)};
return (D < h) ? g : zero;
}
static void hat_dtor(void* context)
{
polymec_free(context);
}
static point_weight_function_t* hat_function_new(real_t h)
{
real_t* Wh = polymec_malloc(sizeof(real_t));
*Wh = h;
point_weight_function_vtable vtable = {.value = hat_W,
.gradient = hat_grad,
.dtor = hat_dtor};
return point_weight_function_new("Hat function", Wh, vtable);
}
static real_t hat_W(void* context, vector_t* y)
{
real_t h = *((real_t*)context); // Spatial extent of W.
real_t D = vector_mag(y);
return (D < h) ? 1.0 - D/h : 0.0;
}
Vector vector_unit(Vector v) {
return vector_scale(v, 1. / vector_mag(v));
}