Function float_pow_test_impl

external/eigen/test/array_cwise.cpp:241–300

template <typename Base, typename Exponent>
void float_pow_test_impl() {
  const Base tol = test_precision<Base>();
  std::vector<Base> abs_base_vals = special_values<Base>();
  std::vector<Exponent> abs_exponent_vals = special_values<Exponent>();
  for (int i = 0; i < 100; i++) {
    abs_base_vals.push_back(internal::random<Base>(Base(0), Base(10)));
    abs_exponent_vals.push_back(internal::random<Exponent>(Exponent(0), Exponent(10)));
  }
  const Index num_repeats = internal::packet_traits<Base>::size + 1;
  ArrayX<Base> bases(num_repeats), eigenPow(num_repeats);
  bool all_pass = true;
  for (Base abs_base : abs_base_vals)
    for (Base base : {negative_or_zero(abs_base), abs_base}) {
      bases.setConstant(base);
      for (Exponent abs_exponent : abs_exponent_vals) {
        for (Exponent exponent : {negative_or_zero(abs_exponent), abs_exponent}) {
          eigenPow = bases.pow(exponent);
          for (Index j = 0; j < num_repeats; j++) {
            Base e = ref_pow<Base, Exponent>::run(bases(j), exponent);
            if (is_integer(exponent)) {
              // std::pow may return an incorrect result for a very large integral exponent
              // if base is negative and the exponent is odd, then the result must be negative
              // if std::pow returns otherwise, flip the sign
              bool exp_is_odd = is_odd(exponent);
              bool base_is_neg = !(numext::isnan)(base) && (bool)numext::signbit(base);
              bool result_is_neg = exp_is_odd && base_is_neg;
              bool ref_is_neg = !(numext::isnan)(e) && (bool)numext::signbit(e);
              bool flip_sign = result_is_neg != ref_is_neg;
              if (flip_sign) e = -e;
            }

            Base a = eigenPow(j);
            #ifdef EIGEN_COMP_MSVC
            // Work around MSVC return value on underflow.
            // if std::pow returns 0 and Eigen returns a denormalized value, then skip the test
            int eigen_fpclass = std::fpclassify(a);
            if (e == Base(0) && eigen_fpclass == FP_SUBNORMAL) continue;
            #endif

            #ifdef EIGEN_VECTORIZE_NEON
            // Work around NEON flush-to-zero mode
            // if std::pow returns denormalized value and Eigen returns 0, then skip the test
            int ref_fpclass = std::fpclassify(e);
            if (a == Base(0) && ref_fpclass == FP_SUBNORMAL) continue;
            #endif

            bool both_nan = (numext::isnan)(a) && (numext::isnan)(e);
            bool exact_or_approx = (a == e) || internal::isApprox(a, e, tol);
            bool same_sign = (bool)numext::signbit(e) == (bool)numext::signbit(a);
            bool success = both_nan || (exact_or_approx && same_sign);
            all_pass &= success;
            if (!success) {
              std::cout << "pow(" << bases(j) << "," << exponent << ")   =   " << a << " !=  " << e << std::endl;
            }
          }
        }
      }
    }