fma(3) — Linux manual page

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | STANDARDS | HISTORY | SEE ALSO | COLOPHON

fma(3)                  Library Functions Manual                  fma(3)

NAME         top

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

LIBRARY         top

       Math library (libm, -lm)

SYNOPSIS         top

       #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         top

       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         top

       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         top

       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         top

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌─────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                           Attribute     Value   │
       ├─────────────────────────────────────┼───────────────┼─────────┤
       │ fma(), fmaf(), fmal()               │ Thread safety │ MT-Safe │
       └─────────────────────────────────────┴───────────────┴─────────┘

STANDARDS         top

       C11, POSIX.1-2008.

HISTORY         top

       glibc 2.1.  C99, POSIX.1-2001.

SEE ALSO         top

       remainder(3), remquo(3)

COLOPHON         top

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Linux man-pages 6.9.1          2024-05-02                         fma(3)