Stan Math Library  2.11.0
reverse mode automatic differentiation
cbrt.hpp
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1 #ifndef STAN_MATH_REV_SCAL_FUN_CBRT_HPP
2 #define STAN_MATH_REV_SCAL_FUN_CBRT_HPP
3 
4 #include <math.h>
5 #include <stan/math/rev/core.hpp>
6 
7 #ifdef _MSC_VER
8 #include <boost/math/special_functions/cbrt.hpp>
10 #endif
11 
12 
13 namespace stan {
14  namespace math {
15 
16  namespace {
17  class cbrt_vari : public op_v_vari {
18  public:
19  explicit cbrt_vari(vari* avi) :
20  op_v_vari(::cbrt(avi->val_), avi) {
21  }
22  void chain() {
23  avi_->adj_ += adj_ / (3.0 * val_ * val_);
24  }
25  };
26  }
27 
56  inline var cbrt(const var& a) {
57  return var(new cbrt_vari(a.vi_));
58  }
59 
60  }
61 }
62 #endif
fvar< T > cbrt(const fvar< T > &x)
Definition: cbrt.hpp:14
Independent (input) and dependent (output) variables for gradients.
Definition: var.hpp:31
vari * vi_
Pointer to the implementation of this variable.
Definition: var.hpp:43
var cbrt(const var &a)
Returns the cube root of the specified variable (C99).
Definition: cbrt.hpp:56

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