NAME

       fma, fmaf, fmal - floating-point multiply and add

SYNOPSIS

       #include <math.h>

       double fma(double x, double y, double z);
       float fmaf(float x, float y, float z);
       long double fmal(long double x, long double y, long double z);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       fma(), fmaf(), fmal():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

DESCRIPTION

       These  functions  compute  x  *  y  +  z.   The result is rounded as one ternary operation
       according to the current rounding mode (see fenv(3)).

RETURN VALUE

       These functions return the value of x * y + z, rounded as one ternary operation.

       If x or y is a NaN, a NaN is returned.

       If x times y is an exact infinity, and z is an infinity with the opposite sign,  a  domain
       error occurs, and a NaN is returned.

       If  one  of  x  or  y  is  an infinity, the other is 0, and z is not a NaN, a domain error
       occurs, and a NaN is returned.

       If one of x or y is an infinity, and the other is 0, and  z  is  a  NaN,  a  domain  error
       occurs, and a NaN is returned.

       If  x  times  y  is  not  an infinity times zero (or vice versa), and z is a NaN, a NaN is
       returned.

       If the result overflows, a range error occurs, and an infinity with the  correct  sign  is
       returned.

       If the result underflows, a range error occurs, and a signed 0 is returned.

ERRORS

       See  math_error(7)  for information on how to determine whether an error has occurred when
       calling these functions.

       The following errors can occur:

       Domain error: x * y + z, or x * y is invalid and z is not a NaN
              An invalid floating-point exception (FE_INVALID) is raised.

       Range error: result overflow
              An overflow floating-point exception (FE_OVERFLOW) is raised.

       Range error: result underflow
              An underflow floating-point exception (FE_UNDERFLOW) is raised.

       These functions do not set errno.

VERSIONS

       These functions first appeared in glibc in version 2.1.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌──────────────────────┬───────────────┬─────────┐
       │Interface             │ Attribute     │ Value   │
       ├──────────────────────┼───────────────┼─────────┤
       │fma(), fmaf(), fmal() │ Thread safety │ MT-Safe │
       └──────────────────────┴───────────────┴─────────┘

CONFORMING TO

       C99, POSIX.1-2001, POSIX.1-2008.

SEE ALSO

       remainder(3), remquo(3)

COLOPHON

       This page is part of release 4.15 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at https://www.kernel.org/doc/man-pages/.

                                            2017-09-15                                     FMA(3)