b2exp

IEEE 754 base-2 exponential function.

Calculates 2^x at exact (1/2 ulp) precision using a 1KB LUT table.

Algorithm

The function first splits the input into whole and fractional parts, and for
each bit in the fractional part accumulates a product of iterative square roots.
The whole part of the input is inserted into the base-2 exponent of the result.

Language

A (semi-)portable version of the function is written in C, and handwritten
assembly versions are written for various operating systems under various
architectures (found in src/asm).

Layout

Each folder of the project contains a about.txt file describing the usage of
the folder and of all files and folders within it.

Compilation

This project is setup on Meson. Once Meson is
installed, b2exp can be compiled like this:

mkdir -p build
meson build
ninja -C build

Instead of build, a different output folder can be used, like output.

Run meson configure build to see the Meson configuration and
meson configure --help to see how to change the configuration.

To install b2exp:

ninja -C build install

It may be necessary to prefix the command with sudo.

Original Work

This project is based on the [LUT algorithm by Claude Baumann
(2004)] (https://www.convict.lu/Jeunes/ultimate_stuff/exp_ln_2.htm). Thanks!

License

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see https://www.gnu.org/licenses.