get_cubic_coefficients_grad Class — pytorch Architecture

Source Code

aten/src/ATen/native/GridSampler.h lines 278–296

template<typename scalar_t>
static inline void get_cubic_coefficients_grad(
    scalar_t coeffs[4],
    scalar_t t) {

  // Must be the same as forward calculation in
  // aten/src/ATen/native/UpSample.h:get_cubic_upsample_coefficients
  scalar_t A = -0.75;

  scalar_t x;
  x = -1 - t; // 1 < x = |-1 - tx| < 2
  coeffs[0] = (-3 * A * x - 10 * A ) * x - 8 * A;
  x = -t;     // x = |0 - tx| <= 1
  coeffs[1] = (-3 * (A + 2) * x - 2 * (A + 3)) * x;
  x = 1 - t;  // x = |1 - tx| <= 1
  coeffs[2] = (3 * (A + 2) * x - 2 * (A + 3)) * x;
  x = 2 - t;  // 1 < x = |2 - tx| < 2
  coeffs[3] = (3 * A * x - 10 * A) * x + 8 * A;
}