fma(3) - f38

1fma(3)                     Library Functions Manual                     fma(3)
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NAME

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

9       Math library (libm, -lm)
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SYNOPSIS

12       #include <math.h>
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14       double fma(double x, double y, double z);
15       float fmaf(float x, float y, float z);
16       long double fmal(long double x, long double y, long double z);
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18   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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20       fma(), fmaf(), fmal():
21           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
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DESCRIPTION

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

28       These functions return the value of x * y + z, rounded as  one  ternary
29       operation.
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31       If x or y is a NaN, a NaN is returned.
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33       If  x times y is an exact infinity, and z is an infinity with the oppo‐
34       site sign, a domain error occurs, and a NaN is returned.
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36       If one of x or y is an infinity, the other is 0, and z is not a NaN,  a
37       domain error occurs, and a NaN is returned.
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39       If  one of x or y is an infinity, and the other is 0, and z is a NaN, a
40       domain error occurs, and a NaN is returned.
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42       If x times y is not an infinity times zero (or vice versa), and z is  a
43       NaN, a NaN is returned.
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45       If the result overflows, a range error occurs, and an infinity with the
46       correct sign is returned.
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48       If the result underflows, a range error occurs, and a signed 0  is  re‐
49       turned.
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ERRORS

52       See  math_error(7) for information on how to determine whether an error
53       has occurred when calling these functions.
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55       The following errors can occur:
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57       Domain error: x * y + z, or x * y is invalid and z is not a NaN
58              An invalid floating-point exception (FE_INVALID) is raised.
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60       Range error: result overflow
61              An overflow floating-point exception (FE_OVERFLOW) is raised.
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63       Range error: result underflow
64              An underflow floating-point exception (FE_UNDERFLOW) is raised.
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66       These functions do not set errno.
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ATTRIBUTES

69       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
70       tributes(7).
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72       ┌────────────────────────────────────────────┬───────────────┬─────────┐
73       │Interface                                   │ Attribute     │ Value   │
74       ├────────────────────────────────────────────┼───────────────┼─────────┤
75       │fma(), fmaf(), fmal()                       │ Thread safety │ MT-Safe │
76       └────────────────────────────────────────────┴───────────────┴─────────┘
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STANDARDS

79       C11, POSIX.1-2008.
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HISTORY

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