1 #ifndef STAN_MATH_REV_SCAL_FUN_PHI_APPROX_HPP 2 #define STAN_MATH_REV_SCAL_FUN_PHI_APPROX_HPP 49 double av_squared = av * av;
50 double av_cubed = av * av_squared;
51 double f =
inv_logit(0.07056 * av_cubed + 1.5976 * av);
52 double da = f * (1 - f) * (3.0 * 0.07056 * av_squared + 1.5976);
fvar< T > inv_logit(const fvar< T > &x)
Returns the inverse logit function applied to the argument.
Independent (input) and dependent (output) variables for gradients.
const double val_
The value of this variable.
fvar< T > Phi_approx(const fvar< T > &x)
Return an approximation of the unit normal cumulative distribution function (CDF).
vari * vi_
Pointer to the implementation of this variable.