1*412f47f9SXin Li// polynomial for approximating log(1+x) in double precision 2*412f47f9SXin Li// 3*412f47f9SXin Li// Copyright (c) 2022-2023, Arm Limited. 4*412f47f9SXin Li// SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception 5*412f47f9SXin Li 6*412f47f9SXin Lideg = 20; 7*412f47f9SXin Li 8*412f47f9SXin Lia = sqrt(2)/2-1; 9*412f47f9SXin Lib = sqrt(2)-1; 10*412f47f9SXin Li 11*412f47f9SXin Lif = proc(y) { 12*412f47f9SXin Li return log(1+y); 13*412f47f9SXin Li}; 14*412f47f9SXin Li 15*412f47f9SXin Liapprox = proc(poly, d) { 16*412f47f9SXin Li return remez(1 - poly(x)/f(x), deg-d, [a;b], x^d/f(x), 1e-10); 17*412f47f9SXin Li}; 18*412f47f9SXin Li 19*412f47f9SXin Lipoly = x; 20*412f47f9SXin Lifor i from 2 to deg do { 21*412f47f9SXin Li p = roundcoefficients(approx(poly,i), [|D ...|]); 22*412f47f9SXin Li poly = poly + x^i*coeff(p,0); 23*412f47f9SXin Li}; 24*412f47f9SXin Li 25*412f47f9SXin Li 26*412f47f9SXin Liprint("coeffs:"); 27*412f47f9SXin Lidisplay = hexadecimal; 28*412f47f9SXin Lifor i from 2 to deg do coeff(poly,i); 29*412f47f9SXin Liprint("rel error:", accurateinfnorm(1-poly(x)/f(x), [a;b], 30)); 30*412f47f9SXin Liprint("in [",a,b,"]"); 31