FMA(3)                                                                  Linux Programmer's Manual                                                                 FMA(3)

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)

                                                                               2021-03-22                                                                         FMA(3)