Stan Math Library  2.15.0
reverse mode automatic differentiation
abs.hpp
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1 #ifndef STAN_MATH_FWD_SCAL_FUN_ABS_HPP
2 #define STAN_MATH_FWD_SCAL_FUN_ABS_HPP
3 
4 #include <stan/math/fwd/core.hpp>
10 
11 namespace stan {
12  namespace math {
13 
14  template<typename T>
15  inline fvar<T> abs(const fvar<T>& x) {
16  if (x.val_ > 0.0)
17  return x;
18  else if (x.val_ < 0.0)
19  return fvar<T>(-x.val_, -x.d_);
20  else if (x.val_ == 0.0)
21  return fvar<T>(0, 0);
22  else
23  return fvar<T>(abs(x.val_), NOT_A_NUMBER);
24  }
25 
26  }
27 }
28 #endif
fvar< T > abs(const fvar< T > &x)
Definition: abs.hpp:15
const double NOT_A_NUMBER
(Quiet) not-a-number value.
Definition: constants.hpp:55

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