Header File 

float.h 

Category 

Math Routines 

Prototype 

double _nextafter(double da, double db); 

long double _nextafterl(long double lda, long double ldb); 

Description 

Takes two doubles (da and db) and returns the closest representable neighbor of da in the direction toward db. 

If da == db, _nextafter returns da, with no exception triggered. If either da or db is a quiet NaN, then the return value is one or the other of the input NaNs. 

_nextafterl is the long double version; it takes a long double argument and returns a long double result. 

Return Value 

Returns the closest representable neighbor of the first argument in the direction toward the second argument. 

Portability