MATH-INTRO(2)MATH-INTRO(2)NAME
Math: intro - elementary numerics
SYNOPSIS
include "math.m";
math := load Math Math->PATH;
DESCRIPTION
Inferno's math module and Limbo compiler provide the fundamental float‐
ing point environment and ``elementary functions''.
Limbo expressions involving only literal and named constants are evalu‐
ated at compile time with all exceptions ignored. However, arithmetic
on variables is left to run-time, even if data path analysis shows the
value to be a compile time constant. This implies that tools generat‐
ing Limbo source must do their own simplification, and not expect the
compiler to change x/x into 1, or -(y-x) into x-y, or even x-0 into x.
Subexpression elimination and other forms of code motion may be done by
the compiler, but not across calls to the mode and status functions
described in math-fp(2). Removal of parentheses or factoring is not
performed by the compiler. The evaluation order of a+b+c follows the
parse tree and is therefore the same as for (a+b)+c. These rules are
the same as for Fortran and C.
Contracted multiply-add instructions (with a single rounding) are not
generated by the compiler, though they may be used in the native BLAS
(linear algebra) libraries. All arithmetic follows the IEEE floating
point standard, except that denormalized numbers may be replaced by
flush-to-0, depending on what the hardware makes feasible.
Binary/decimal conversion is properly rounded. In particular, printing
a real using %g and reading it on a different machine is guaranteed to
recover identical bits, including conversions done by the compiler.
The one exception is that smaller, faster, but sloppier run-time con‐
version routines may be used when mandated by limited memory embedded
systems. Programmers may assume, however, that the features described
in these man pages are present in all Inferno systems intended for gen‐
eral computing.
SOURCE
/libinterp/math.c
SEE ALSO
See math-fp(2) for floating point control and primitive arithmetic
operations, math-elem(2) for the classical elementary functions of
applied mathematics, and math-linalg(2) for basic linear algebra func‐
tions.
MATH-INTRO(2)
