// Mahalanobis distance
float nv_mahalanobis(const nv_cov_t *cov, const nv_matrix_t *x, int xm)
{
int n;
nv_matrix_t *y = nv_matrix_alloc(x->n, 1);
nv_matrix_t *x2 = nv_matrix_alloc(x->n, 1);
float distance;
float delta2 = 0.0f;
nv_matrix_zero(y);
nv_matrix_zero(x2);
for (n = 0; n < x2->n; ++n) {
NV_MAT_V(x2, 0, n) = NV_MAT_V(x, xm, n) - NV_MAT_V(cov->u, 0, n);
}
nv_gemv(y, 0, NV_MAT_TR, cov->eigen_vec, x2, xm);
for (n = 0; n < x->n; ++n) {
float ev = NV_MAT_V(cov->eigen_val, n, 0);
float xv = NV_MAT_V(y, 0, n);
delta2 += (xv * xv) / ev;
}
distance = sqrtf(delta2);
nv_matrix_free(&x2);
nv_matrix_free(&y);
return distance;
}
static float tangent_angle(float r,
float y, float x,
const nv_matrix_t *points, int pc)
{
int i, dot_m = 0;
float tan_angle;
int info;
#if 0
nv_matrix_t *dot = nv_matrix_alloc(2, (int)(2.0f * r * 2.0f *r));
#else
nv_matrix_t *dot = nv_matrix_alloc(2, 10 * 8);
#endif
nv_matrix_t *test_val = nv_matrix_alloc(2, 1);
nv_matrix_t *test_ret = nv_matrix_alloc(2, 1);
nv_cov_t *cov = nv_cov_alloc(2);
NV_MAT_V(dot, 0, 0) = 0.0f;
NV_MAT_V(dot, 0, 1) = 0.0f;
++dot_m;
for (i = 0; i < pc; ++i) {
float dy = NV_MAT_V(points, i, 0) - y;
float dx = NV_MAT_V(points, i, 1) - x;
#if 0
if ((dx * dx + dy * dy) <= r * r) {
#else
if ((dx * dx + dy * dy) <= 4.0f * 4.0f) {
#endif
NV_MAT_V(dot, dot_m, 0) = dy;
NV_MAT_V(dot, dot_m, 1) = dx;
++dot_m;
}
}
nv_matrix_m(dot, dot_m);
nv_cov(cov->cov, cov->u, cov->s, dot);
info = nv_eigen_sym(cov->eigen_vec, cov->eigen_val, cov->cov, 50);
NV_MAT_V(test_val, 0, 0) = 0.0f;
NV_MAT_V(test_val, 0, 1) = 1.0f;
nv_gemv(test_ret, 0, NV_MAT_TR, cov->eigen_vec, test_val, 0);
y = NV_MAT_V(test_ret, 0, 0);
x = NV_MAT_V(test_ret, 0, 1);
/*
if (x < 0.0f) {
x *= -1.0f;
y *= -1.0f;
}
*/
tan_angle = atan2f(x, y);
/*
if (tan_angle < 0.0f) {
tan_angle = 2.0f * NV_PI + tan_angle;
}
*/
nv_matrix_free(&dot);
nv_matrix_free(&test_val);
nv_matrix_free(&test_ret);
nv_cov_free(&cov);
return tan_angle;
}
#endif
nv_shapecontext_t *nv_shapecontext_alloc(int n)
{
nv_shapecontext_t *sctx = (nv_shapecontext_t *)nv_malloc(sizeof(nv_shapecontext_t));
sctx->sctx = nv_matrix3d_list_alloc(1, NV_SC_LOG_R_BIN, NV_SC_THETA_BIN, n);
sctx->tan_angle = nv_matrix_alloc(1, n);
sctx->coodinate = nv_matrix_alloc(2, n);
sctx->radius = nv_matrix_alloc(1, n);
return sctx;
}
