1// polynomial for approximating atan(x) and atan2(y, x) 2// 3// Copyright (c) 2022-2023, Arm Limited. 4// SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception 5 6// atan is odd, so approximate with an odd polynomial: 7// x + ax^3 + bx^5 + cx^7 + ... 8// We generate a, b, c, ... such that we can approximate atan(x) by: 9// x + x^3 * (a + bx^2 + cx^4 + ...) 10 11// Assemble monomials 12deg = 20; 13mons = [|1,...,deg|]; 14for i from 0 to deg-1 do mons[i] = mons[i] * 2 + 1; 15 16a = 0x1.0p-1022; 17b = 1; 18 19poly = fpminimax(atan(x)-x, mons, [|double ...|], [a;b]); 20 21display = hexadecimal; 22print("coeffs:"); 23for i from 0 to deg-1 do coeff(poly,mons[i]); 24