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std::fma

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Revision as of 23:17, 31 May 2013 by P12bot (Talk | contribs)

 
 
 
Common mathematical functions
Functions
Basic operations
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fma
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Defined in header <cmath>
float       fma( float x, float y, float z );
(1) (since C++11)
double      fma( double x, double y, double z );
(2) (since C++11)
long double fma( long double x, long double y, long double z );
(3) (since C++11)
Promoted    fma( Arithmetic x, Arithmetic y, Arithmetic z );
(4) (since C++11)
#define FP_FAST_FMA  /* implementation-defined */
(5) (since C++11)
#define FP_FAST_FMAF /* implementation-defined */
(6) (since C++11)
#define FP_FAST_FMAL /* implementation-defined */
(7) (since C++11)

The fma functions compute (x*y) + z, rounded as one ternary operation, according to the rounding mode characterized by the value of FLT_ROUNDS.

4) If any argument has integral type, it is cast to double. If any other argument is long double, then the return type is long double, otherwise it is double.

5-7) If the macro constants FP_FAST_FMAF, FP_FAST_FMA, or FP_FAST_FMAL are defined, the function std::fma evaluates faster than the expression x*y+z for float, double, and long double arguments, respectively. If defined, these macros evaluate to integer 1.

Parameters

x, y, z - floating point values

Return value

(x*y) + z, rounded as one ternary operation

See also

(C++11)
signed remainder of the division operation
(function) [edit]
(C++11)
signed remainder as well as the three last bits of the division operation
(function) [edit]