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finite_diff_gradient.hpp
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1 #ifndef STAN_MATH_PRIM_MAT_FUNCTOR_FINITE_DIFF_GRADIENT_HPP
2 #define STAN_MATH_PRIM_MAT_FUNCTOR_FINITE_DIFF_GRADIENT_HPP
3
4 #include <stan/math/prim/mat/fun/Eigen.hpp>
5
6 namespace stan {
7 namespace math {
8
36 template <typename F>
37 void
38 finite_diff_gradient(const F& f,
39 const Eigen::Matrix<double, -1, 1>& x,
40 double& fx,
41 Eigen::Matrix<double, -1, 1>& grad_fx,
42 const double epsilon = 1e-03) {
43 using Eigen::Matrix;
44 using Eigen::Dynamic;
45 Matrix<double, Dynamic, 1> x_temp(x);
46
47 int d = x.size();
48 grad_fx.resize(d);
49
50 fx = f(x);
51
52 for (int i = 0; i < d; ++i) {
53 double delta_f = 0.0;
54
55 x_temp(i) = x(i) + 3.0 * epsilon;
56 delta_f = f(x_temp);
57
58 x_temp(i) = x(i) + 2.0 * epsilon;
59 delta_f -= 9.0 * f(x_temp);
60
61 x_temp(i) = x(i) + epsilon;
62 delta_f += 45.0 * f(x_temp);
63
64 x_temp(i) = x(i) + -3.0 * epsilon;
65 delta_f -= f(x_temp);
66
67 x_temp(i) = x(i) + -2.0 * epsilon;
68 delta_f += 9.0 * f(x_temp);
69
70 x_temp(i) = x(i) + -epsilon;
71 delta_f -= 45.0 * f(x_temp);
72
73 delta_f /= 60 * epsilon;
74
75 x_temp(i) = x(i);
76 grad_fx(i) = delta_f;
77 }
78 }
79 }
80 }
81 #endif
stan
Definition: log_sum_exp.hpp:8
Eigen.hpp
stan::math::e
double e()
Return the base of the natural logarithm.
Definition: constants.hpp:94
stan::math::finite_diff_gradient
void finite_diff_gradient(const F &f, const Eigen::Matrix< double,-1, 1 > &x, double &fx, Eigen::Matrix< double,-1, 1 > &grad_fx, const double epsilon=1e-03)
Calculate the value and the gradient of the specified function at the specified argument using finite...
Definition: finite_diff_gradient.hpp:38

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