C Programming on the IBM PC (C Programmers Reference Guide Series)

fma

#include <math.h>float fmaf(float a, float b, float c);double fma(double a, double b, double c); long double fmal(long double a, long double b, long                 double c);

fma( ), fmaf( ), and fmal( ) were defined by C99.

The fma( ) family of functions returns the value of a * b + c. Rounding takes place only once, after the entire operation has been completed.

Related functions are round( ), lround( ), and llround( ).