1 #ifndef STAN_MATH_PRIM_MAT_FUN_UNIT_VECTOR_CONSTRAIN_HPP 2 #define STAN_MATH_PRIM_MAT_FUN_UNIT_VECTOR_CONSTRAIN_HPP 17 class unit_vector_elt_vari :
public vari {
20 const double* unit_vector_y_;
26 unit_vector_elt_vari(
double val,
28 const double* unit_vector_y,
34 unit_vector_y_(unit_vector_y),
40 const double cubed_norm = norm_ * norm_ * norm_;
41 for (
int m = 0; m <
size_; ++m) {
43 -= adj_ * unit_vector_y_[m] * unit_vector_y_[idx_] / cubed_norm;
45 y_[m]->adj_ += adj_ / norm_;
59 template <
int R,
int C>
60 Eigen::Matrix<var, R, C>
68 for (
int i = 0; i < y.size(); ++i)
69 y_vi_array[i] = y.coeff(i).vi_;
71 Eigen::VectorXd y_d(y.size());
72 for (
int i = 0; i < y.size(); ++i)
73 y_d.coeffRef(i) = y.coeff(i).val();
75 const double norm = y_d.norm();
77 Eigen::VectorXd unit_vector_d = y_d / norm;
79 double* unit_vector_y_d_array
81 .
alloc(
sizeof(
double) * y_d.size()));
82 for (
int i = 0; i < y_d.size(); ++i)
83 unit_vector_y_d_array[i] = unit_vector_d.coeff(i);
85 Eigen::Matrix<var, R, C> unit_vector_y(y.size());
86 for (
int k = 0; k < y.size(); ++k)
87 unit_vector_y.coeffRef(k)
88 =
var(
new unit_vector_elt_vari(unit_vector_d[k],
90 unit_vector_y_d_array,
106 template <
int R,
int C>
107 Eigen::Matrix<var, R, C>
void check_nonzero_size(const char *function, const char *name, const T_y &y)
Check if the specified matrix/vector is of non-zero size.
static stack_alloc memalloc_
The variable implementation base class.
void check_vector(const char *function, const char *name, const Eigen::Matrix< T, R, C > &x)
Check if the matrix is either a row vector or column vector.
Independent (input) and dependent (output) variables for gradients.
fvar< T > dot_self(const Eigen::Matrix< fvar< T >, R, C > &v)
Eigen::Matrix< fvar< T >, R, C > unit_vector_constrain(const Eigen::Matrix< fvar< T >, R, C > &y)
void check_positive_finite(const char *function, const char *name, const T_y &y)
Check if y is positive and finite.
int size(const std::vector< T > &x)
Return the size of the specified standard vector.
void * alloc(size_t len)
Return a newly allocated block of memory of the appropriate size managed by the stack allocator...