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squared_distance.hpp
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1 #ifndef STAN_MATH_REV_MAT_FUN_SQUARED_DISTANCE_HPP
2 #define STAN_MATH_REV_MAT_FUN_SQUARED_DISTANCE_HPP
3
4 #include <stan/math/rev/core.hpp>
5 #include <stan/math/rev/scal/fun/sqrt.hpp>
6 #include <stan/math/rev/mat/fun/typedefs.hpp>
7 #include <stan/math/prim/mat/err/check_vector.hpp>
8 #include <stan/math/prim/mat/err/check_matching_sizes.hpp>
9 #include <stan/math/prim/mat/fun/Eigen.hpp>
10 #include <stan/math/prim/mat/fun/typedefs.hpp>
11 #include <stan/math/prim/mat/meta/index_type.hpp>
12 #include <stan/math/prim/arr/meta/index_type.hpp>
13 #include <stan/math/prim/scal/meta/index_type.hpp>
14 #include <vector>
15
16 namespace stan {
17
18 namespace math {
19
20 namespace {
21
22 class squared_distance_vv_vari : public vari {
23 protected:
24 vari** v1_;
25 vari** v2_;
26 size_t length_;
27
28 template <int R1, int C1, int R2, int C2>
29 inline static double
30 var_squared_distance(const Eigen::Matrix<var, R1, C1> &v1,
31 const Eigen::Matrix<var, R2, C2> &v2) {
32 using Eigen::Matrix;
33 using stan::math::index_type;
34 typedef typename index_type<Matrix<var, R1, R2> >::type idx_t;
35 double result = 0;
36 for (idx_t i = 0; i < v1.size(); i++) {
37 double diff = v1(i).vi_->val_ - v2(i).vi_->val_;
38 result += diff*diff;
39 }
40 return result;
41 }
42
43 public:
44 template<int R1, int C1, int R2, int C2>
45 squared_distance_vv_vari(const Eigen::Matrix<var, R1, C1> &v1,
46 const Eigen::Matrix<var, R2, C2> &v2)
47 : vari(var_squared_distance(v1, v2)), length_(v1.size()) {
48 v1_ = reinterpret_cast<vari**>(ChainableStack::memalloc_
49 .alloc(length_*sizeof(vari*)));
50 for (size_t i = 0; i < length_; i++)
51 v1_[i] = v1(i).vi_;
52
53 v2_ = reinterpret_cast<vari**>(ChainableStack::memalloc_
54 .alloc(length_*sizeof(vari*)));
55 for (size_t i = 0; i < length_; i++)
56 v2_[i] = v2(i).vi_;
57 }
58 virtual void chain() {
59 for (size_t i = 0; i < length_; i++) {
60 double di = 2 * adj_ * (v1_[i]->val_ - v2_[i]->val_);
61 v1_[i]->adj_ += di;
62 v2_[i]->adj_ -= di;
63 }
64 }
65 };
66 class squared_distance_vd_vari : public vari {
67 protected:
68 vari** v1_;
69 double* v2_;
70 size_t length_;
71
72 template<int R1, int C1, int R2, int C2>
73 inline static double
74 var_squared_distance(const Eigen::Matrix<var, R1, C1> &v1,
75 const Eigen::Matrix<double, R2, C2> &v2) {
76 using Eigen::Matrix;
77 using stan::math::index_type;
78 typedef typename index_type<Matrix<double, R1, C1> >::type idx_t;
79
80 double result = 0;
81 for (idx_t i = 0; i < v1.size(); i++) {
82 double diff = v1(i).vi_->val_ - v2(i);
83 result += diff*diff;
84 }
85 return result;
86 }
87
88 public:
89 template<int R1, int C1, int R2, int C2>
90 squared_distance_vd_vari(const Eigen::Matrix<var, R1, C1> &v1,
91 const Eigen::Matrix<double, R2, C2> &v2)
92 : vari(var_squared_distance(v1, v2)), length_(v1.size()) {
93 v1_ = reinterpret_cast<vari**>(ChainableStack::memalloc_
94 .alloc(length_*sizeof(vari*)));
95 for (size_t i = 0; i < length_; i++)
96 v1_[i] = v1(i).vi_;
97
98 v2_ = reinterpret_cast<double*>(ChainableStack::memalloc_
99 .alloc(length_*sizeof(double)));
100 for (size_t i = 0; i < length_; i++)
101 v2_[i] = v2(i);
102 }
103 virtual void chain() {
104 for (size_t i = 0; i < length_; i++) {
105 v1_[i]->adj_ += 2 * adj_ * (v1_[i]->val_ - v2_[i]);
106 }
107 }
108 };
109 }
110
111 template<int R1, int C1, int R2, int C2>
112 inline var squared_distance(const Eigen::Matrix<var, R1, C1>& v1,
113 const Eigen::Matrix<var, R2, C2>& v2) {
114 stan::math::check_vector("squared_distance", "v1", v1);
115 stan::math::check_vector("squared_distance", "v2", v2);
116 stan::math::check_matching_sizes("squared_distance",
117 "v1", v1,
118 "v2", v2);
119 return var(new squared_distance_vv_vari(v1, v2));
120 }
121 template<int R1, int C1, int R2, int C2>
122 inline var squared_distance(const Eigen::Matrix<var, R1, C1>& v1,
123 const Eigen::Matrix<double, R2, C2>& v2) {
124 stan::math::check_vector("squared_distance", "v1", v1);
125 stan::math::check_vector("squared_distance", "v2", v2);
126 stan::math::check_matching_sizes("squared_distance",
127 "v1", v1,
128 "v2", v2);
129 return var(new squared_distance_vd_vari(v1, v2));
130 }
131 template<int R1, int C1, int R2, int C2>
132 inline var squared_distance(const Eigen::Matrix<double, R1, C1>& v1,
133 const Eigen::Matrix<var, R2, C2>& v2) {
134 stan::math::check_vector("squared_distance", "v1", v1);
135 stan::math::check_vector("squared_distance", "v2", v2);
136 stan::math::check_matching_sizes("squared_distance",
137 "v1", v1,
138 "v2", v2);
139 return var(new squared_distance_vd_vari(v2, v1));
140 }
141 }
142 }
143 #endif
core.hpp
stan::math::check_vector
bool check_vector(const char *function, const char *name, const Eigen::Matrix< T, R, C > &x)
Return true if the matrix is either a row vector or column vector.
Definition: check_vector.hpp:34
index_type.hpp
stan::math::AutodiffStackStorage::memalloc_
static stack_alloc memalloc_
Definition: autodiffstackstorage.hpp:16
stan::math::squared_distance
boost::math::tools::promote_args< T1, T2 >::type squared_distance(const Eigen::Matrix< T1, R1, C1 > &v1, const Eigen::Matrix< T2, R2, C2 > &v2)
Returns the squared distance between the specified vectors.
Definition: squared_distance.hpp:22
index_type.hpp
v1_
vari ** v1_
Definition: squared_distance.hpp:24
check_matching_sizes.hpp
stan::math::var
Independent (input) and dependent (output) variables for gradients.
Definition: var.hpp:32
sqrt.hpp
stan::math::index_type
Primary template class for the metaprogram to compute the index type of a container.
Definition: index_type.hpp:19
length_
size_t length_
Definition: squared_distance.hpp:26
index_type.hpp
typedefs.hpp
stan::math::check_matching_sizes
bool check_matching_sizes(const char *function, const char *name1, const T_y1 &y1, const char *name2, const T_y2 &y2)
Return true if two structures at the same size.
Definition: check_matching_sizes.hpp:29
Eigen.hpp
check_vector.hpp
v2_
vari ** v2_
Definition: squared_distance.hpp:25
stan::math::size
int size(const std::vector< T > &x)
Definition: size.hpp:11
stan::math::stack_alloc::alloc
void * alloc(size_t len)
Return a newly allocated block of memory of the appropriate size managed by the stack allocator...
Definition: stack_alloc.hpp:170
typedefs.hpp

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