xref: /freebsd-src/contrib/arm-optimized-routines/math/tools/log1pf.sollya (revision f3087bef11543b42e0d69b708f367097a4118d24)
1*f3087befSAndrew Turner// polynomial for approximating log(1+x) in single precision
2*f3087befSAndrew Turner//
3*f3087befSAndrew Turner// Copyright (c) 2022-2024, Arm Limited.
4*f3087befSAndrew Turner// SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
5*f3087befSAndrew Turner
6*f3087befSAndrew Turnerdeg = 10;
7*f3087befSAndrew Turner
8*f3087befSAndrew Turnera = -0.25;
9*f3087befSAndrew Turnerb = 0.5;
10*f3087befSAndrew Turner
11*f3087befSAndrew Turnerf = proc(y) {
12*f3087befSAndrew Turner  return log(1+y);
13*f3087befSAndrew Turner};
14*f3087befSAndrew Turner
15*f3087befSAndrew Turnerpoly = fpminimax(f(x), deg, [|single ...|], [a;b]);
16*f3087befSAndrew Turner
17*f3087befSAndrew Turnerdisplay = hexadecimal;
18*f3087befSAndrew Turnerprint("rel error:", accurateinfnorm(1-poly(x)/f(x), [a;b], 30));
19*f3087befSAndrew Turnerprint("in [",a,b,"]");
20*f3087befSAndrew Turnerprint("coeffs:");
21*f3087befSAndrew Turnerfor i from 2 to deg do round(coeff(poly,i), SG, RN);
22