multiplicative-expression

multiplicative-expression * cast-expression

assignment-expression

unary-expression assignment-operator assignment-expression

assignment-operator

*=

The operator * performs multiplication. Its operands must be of arithmetic type. Standard arithmetic promotions are applied to the operands.

#include <math.h>
float fmaf(float x, float y, float z);
double fma(double x, double y, double z);
long double fmal(long double x, long double y, long double z);

#include <tgmath.h>
real-floating-type fma(real-floating-type x, real-floating-type y, real-floating-type z);

The fma functions return xy+z. If FP_FAST_FMA is defined and expands to 1, it is likely that fma will be faster than an expression of the form x * y + z with operands of type double. FP_FAST_FMAF is similarly defined for fmaf and float, and FP_FAST_FMAL is similarly defined for fmal and long double.

#include <math.h>
float scalbnf(float x, int n);
double scalbn(double x, int n);
long double scalbnl(long double x, int n);
float scalblnf(float x, long n);
double scalbln(double x, long n);
long double scalblnl(long double x, long n);

#include <tgmath.h>
real-floating-type scalbn(real-floating-type x, int n);
real-floating-type scalbln(real-floating-type x, long n);

The scalbn and scalbln functions compute xbⁿ, where b is FLT_RADIX. They should be able to do this more efficiently than by calling pow (say), because they just need to modify the exponent.