_beta_grad_beta_small Class — pytorch Architecture

Source Code

aten/src/ATen/native/Distributions.h lines 390–403

template <typename scalar_t, typename accscalar_t>
C10_DEVICE inline scalar_t _beta_grad_beta_small(scalar_t x, scalar_t alpha, scalar_t beta) {
  const scalar_t factor = digamma_one<scalar_t, accscalar_t>(alpha + beta) - digamma_one<scalar_t, accscalar_t>(beta);
  scalar_t numer = 1, betas = 1, dbetas = 0, series = factor / alpha;
  for (int i = 1; i <= 8; ++i) {
    scalar_t casted_i = static_cast<scalar_t>(i);
    numer *= -x / casted_i;
    dbetas = dbetas * (beta - casted_i) + betas;
    betas = betas * (beta - casted_i);
    series += numer / (alpha + casted_i) * (dbetas + factor * betas);
  }
  const scalar_t result = -compat_pow(1 - x, 1 - beta) * series;
  return isnan(result) ? static_cast<scalar_t>( 0.f ) : result;
}