FORTRAN SOFTWARE CATALOG

Repository owner: Federico Perini (perazz)

fastmath

Approximate exponential, logarithm and inverse-square-root functions.

Repository · Pinned source (ad0f14c45520) · Try in playground · Checked package example

GAMS classifications

About this package

Category
General utilities
License
MIT

Topics: approximate-math, elementary-functions, exponential, exponential-functions, fast-math, fortran, logarithm, logarithms, rsqrt

Package dependencies

Resolved GitHub repositories used by the verified playground build, combining direct and indirect dependencies. This list does not describe internal module dependencies or native system libraries.

Required by this build

No additional GitHub package dependencies were recorded for this verified build.

Build record verified 2026-10-28.

Used by (0 selected packages)

No other selected build records this repository as a dependency. This is not a measure of usage outside the catalog.

Reviewed procedures

These mappings have pinned source evidence. A checked package example may exercise only some of them; source review is not a numerical benchmark.

fexp; fast_log / flog_quintic

Module: fast_exp / fast_log

C4b

C4b: verified

Derivatives / callbacks: not applicable

Approximate exponential/logarithm evaluation; accuracy differs from standard intrinsics. Independent consumer checks fexp and flog_quintic at 641 grid points from -80 to 80, using intrinsic exp and the known inverse arguments as references. Explicit approximation tolerances, positivity, finite results, scalar/array agreement and grid monotonicity are enforced. This is not a speed benchmark or an accuracy guarantee outside the tested normal finite range.

Pinned source: src/fast_exp.f90 · src/fast_log.f90

Author examples/tests: test/test.f90

Load checked GAMS driver: gams-fastmath-exp-log-reference

frsqrt

Module: fast_rsqrt

C2

C2: verified

Derivatives / callbacks: not applicable

Approximate reciprocal square root, with documented accuracy tradeoffs. Independent consumer checks 168 exactly representable dyadic squares using reciprocals of their known roots, over root binary exponents -250..250 and eight mantissas. Finite positive results, scalar/array agreement and normalized equation residuals are required. Zero, negative, subnormal, infinity/NaN arguments and speed are not verified.

Pinned source: src/fast_rsqrt.f90

Author examples/tests: test/test.f90

Load checked GAMS driver: gams-fastmath-rsqrt-reference