fma(3)                     Library Functions Manual                     fma(3)

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

LIBRARY
       Math library (libm, -lm)

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);

   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.

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

       +--------------------------------------------+---------------+---------+
       |Interface                                   | Attribute     | Value   |
       +--------------------------------------------+---------------+---------+
       |fma (), fmaf (), fmal ()                    | Thread safety | MT-Safe |
       +--------------------------------------------+---------------+---------+
STANDARDS
       C11, POSIX.1-2008.

HISTORY
       glibc 2.1.  C99, POSIX.1-2001.

SEE ALSO
       remainder(3), remquo(3)

Linux man-pages 6.7               2023-10-31                            fma(3)