1 #ifndef STAN_MATH_PRIM_MAT_FUN_UNIT_VECTOR_FREE_HPP
2 #define STAN_MATH_PRIM_MAT_FUN_UNIT_VECTOR_FREE_HPP
15 Eigen::Matrix<T, Eigen::Dynamic, 1>
21 "Unit vector variable", x);
22 int Km1 = x.size() - 1;
23 Matrix<T, Dynamic, 1> y(Km1);
24 T sumSq = x(Km1)*x(Km1);
25 const T half_pi = T(M_PI/2.0);
26 for (
int k = Km1; --k >= 0; ) {
27 y(k) =
atan2(
sqrt(sumSq), x(k)) - half_pi;
fvar< T > sqrt(const fvar< T > &x)
fvar< T > atan2(const fvar< T > &x1, const fvar< T > &x2)
bool check_unit_vector(const char *function, const char *name, const Eigen::Matrix< T_prob, Dynamic, 1 > &theta)
Return true if the specified vector is unit vector.
Eigen::Matrix< T, Eigen::Dynamic, 1 > unit_vector_free(const Eigen::Matrix< T, Eigen::Dynamic, 1 > &x)