_beta_grad_alpha_small Class — pytorch Architecture

Source Code

aten/src/ATen/native/Distributions.h lines 372–386

template <typename scalar_t, typename accscalar_t>
C10_DEVICE inline scalar_t _beta_grad_alpha_small(scalar_t x, scalar_t alpha, scalar_t beta) {
  const scalar_t factor = digamma_one<scalar_t, accscalar_t>(alpha)
                        - digamma_one<scalar_t, accscalar_t>(alpha + beta) - compat_log(x);
  scalar_t numer = 1;
  scalar_t series = numer / alpha * (factor + 1 / alpha);
  for (int i = 1; i <= 10; ++i) {
    scalar_t casted_i = static_cast<scalar_t>(i);
    numer *= (casted_i - beta) * x / casted_i;
    const scalar_t denom = alpha + casted_i;
    series += numer / denom * (factor + 1 / denom);
  }
  const scalar_t result = x * compat_pow(1 - x, -beta) * series;
  return isnan(result) ? static_cast<scalar_t>( 0.f ) : result;
}