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

**#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

These functions compute

*x* *

*y* +

*z*. The result is rounded as
one ternary operation according to the current rounding mode (see

**fenv**(3)).

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.

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*.

These functions first appeared in glibc in version 2.1.

For an explanation of the terms used in this section, see

**attributes**(7).

Interface |
Attribute |
Value |

fma (), fmaf (), fmal () |
Thread safety |
MT-Safe |

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

**remainder**(3),

**remquo**(3)