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 floating point environment and ``elementary
functions''.
Limbo expressions involving only literal and named constants
are evaluated 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 generating 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 round-
ing) 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 particu-
lar, 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 conversion routines
may be used when mandated by limited memory embedded sys-
tems. Programmers may assume, however, that the features
described in these man pages are present in all Inferno sys-
tems intended for general computing.
SOURCE
/interp/math.c
SEE ALSO
Page 1 Plan 9 (printed 12/21/24)
MATH-INTRO(2) MATH-INTRO(2)
See math-fp(2) for floating point control and primitive
arithmetic operations, math-elem(2) for the classical ele-
mentary functions of applied mathematics, and math-linalg(2)
for basic linear algebra functions.
Page 2 Plan 9 (printed 12/21/24)