llvm/libc/src/math/generic/inv_trigf_utils.h

//===-- Single-precision general inverse trigonometric functions ----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIBC_SRC_MATH_GENERIC_INV_TRIGF_UTILS_H
#define LLVM_LIBC_SRC_MATH_GENERIC_INV_TRIGF_UTILS_H

#include "src/__support/FPUtil/PolyEval.h"
#include "src/__support/FPUtil/multiply_add.h"
#include "src/__support/common.h"
#include "src/__support/macros/config.h"

namespace LIBC_NAMESPACE_DECL {

// PI and PI / 2
constexpr double M_MATH_PI = …;
constexpr double M_MATH_PI_2 = …;

extern double ATAN_COEFFS[17][9];

// For |x| <= 1/32 and 0 <= i <= 16, return Q(x) such that:
//   Q(x) ~ (atan(x + i/16) - atan(i/16)) / x.
LIBC_INLINE double atan_eval(double x, int i) { … }

// > Q = fpminimax(asin(x)/x, [|0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20|],
//                 [|1, D...|], [0, 0.5]);
constexpr double ASIN_COEFFS[10] = …;

// Evaluate P(x^2) - 1, where P(x^2) ~ asin(x)/x
LIBC_INLINE double asin_eval(double xsq) { … }

} // namespace LIBC_NAMESPACE_DECL

#endif // LLVM_LIBC_SRC_MATH_GENERIC_INV_TRIGF_UTILS_H