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author | Elliott Hughes <enh@google.com> | 2023-01-25 16:31:42 +0000 |
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committer | Elliott Hughes <enh@google.com> | 2023-01-25 18:11:56 +0000 |
commit | 62662f115a17a5548402fcd02f3b7e1b9b38e087 (patch) | |
tree | 945eb1832687ad5eb97c433013617dbe107718e5 /pl/math/tools/log10f.sollya | |
parent | 04d0bc466ce39c702459d77a15754a19533eaec9 (diff) | |
parent | 56e3bf05c19c4e28e1f5edd9093c712f16c5c32a (diff) | |
download | arm-optimized-routines-62662f115a17a5548402fcd02f3b7e1b9b38e087.tar.gz |
Upgrade ARM-software/optimized-routines to v23.01
This project was upgraded with external_updater.
Usage: tools/external_updater/updater.sh update arm-optimized-routines
For more info, check https://cs.android.com/android/platform/superproject/+/master:tools/external_updater/README.md
Test: TreeHugger
Change-Id: I03de0ecb0ea89c2a77b1c411685af09fd480b63e
Diffstat (limited to 'pl/math/tools/log10f.sollya')
-rw-r--r-- | pl/math/tools/log10f.sollya | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/pl/math/tools/log10f.sollya b/pl/math/tools/log10f.sollya new file mode 100644 index 0000000..94bf32f --- /dev/null +++ b/pl/math/tools/log10f.sollya @@ -0,0 +1,37 @@ +// polynomial for approximating log10f(1+x) +// +// Copyright (c) 2019-2023, Arm Limited. +// SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception + +// Computation of log10f(1+x) will be carried out in double precision + +deg = 4; // poly degree +// [OFF; 2*OFF] is divided in 2^4 intervals with OFF~0.7 +a = -0.04375; +b = 0.04375; + +// find log(1+x)/x polynomial with minimal relative error +// (minimal relative error polynomial for log(1+x) is the same * x) +deg = deg-1; // because of /x + +// f = log(1+x)/x; using taylor series +f = 0; +for i from 0 to 60 do { f = f + (-x)^i/(i+1); }; + +// return p that minimizes |f(x) - poly(x) - x^d*p(x)|/|f(x)| +approx = proc(poly,d) { + return remez(1 - poly(x)/f(x), deg-d, [a;b], x^d/f(x), 1e-10); +}; + +// first coeff is fixed, iteratively find optimal double prec coeffs +poly = 1; +for i from 1 to deg do { + p = roundcoefficients(approx(poly,i), [|D ...|]); + poly = poly + x^i*coeff(p,0); +}; + +display = hexadecimal; +print("rel error:", accurateinfnorm(1-poly(x)/f(x), [a;b], 30)); +print("in [",a,b,"]"); +print("coeffs:"); +for i from 0 to deg do double(coeff(poly,i)); |