intro(3M)                      DG/UX R4.11MU05                     intro(3M)


NAME
       intro - introduction to math libraries

SYNOPSIS
       cc [flag ...] file ...  -lm [library ...]

       #include <math.h>

DESCRIPTION
       This section describes the functions in the math library libm.
       Declarations for these functions may be obtained from the #include
       file math.h.  Several generally useful mathematical constants are
       also defined there [see intro(3) and math(5)].

       The math libraries are not automatically loaded by the C compilation
       system; use the -l option to cc to access the libraries as follows:

               -lm       Search the regular math library, libm.

       libm    Contains the full set of double-precision routines plus some
               single-precision routines (designated by the suffix f) that
               give better performance with less precision.  Selected
               routines are hand-optimized for performance.  The optimized
               routines include sin, cos, tan, atan, atan2, exp, log, log10,
               pow, and sqrt and their single-precision equivalents.

DEFINITIONS
       See intro(3) for C language definitions.

FILES
       LIBDIR                  usually /usr/lib
       LIBDIR/libm.a
SEE ALSO
       cc(1), intro(2), intro(3), math(5).
       The ``Floating Point Operations'' chapter in the Programmer's Guide:
       ANSI C and Programming Support Tools.
DIAGNOSTICS
       Error handling varies according to compilation mode.  Under the -Xt
       option to cc, these functions return the conventional values 0,
       ±HUGE, or NaN when the function is undefined for the given arguments
       or when the value is not representable.  In the -Xa (default) and -Xc
       compilation modes, ±HUGEVAL is returned instead of ±HUGE.  (HUGEVAL
       and HUGE are defined in math.h to be infinity and the largest-
       magnitude single-precision number, respectively.)  In every case, the
       external variable errno [see intro(2)] is set to the value EDOM or
       ERANGE, although the value may vary for a given error depending on
       compilation mode.  See the table under matherr(3M) below.


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