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modf, modff, modfl - decompose floating-point number

c99 [ flag... ] file... -lm [ library... ]
#include <math.h>

double modf(double x, double *iptr);

float modff(float x, float *iptr);

long double modfl(long double x, long double *iptr);

These functions break the argument x into integral and fractional parts, each of which has the same sign as the argument. It stores the integral part as a double for the modf() function, a float for the modff() function, or a long double for the modfl() function in the object pointed to by iptr. Upon successful completion, these functions return the signed fractional part of x.

If x is NaN, a NaN is returned and *iptr is set to NaN.

If x is \(+-Inf, \(+-0 is returned and *iptr is set to \(+-Inf.

No errors are defined. These functions compute the function result and *iptr such that:

a = modf(x, &iptr) ;
x == a+*iptr ;

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE

Interface Stability Standard

MT-Level MT-Safe

frexp (3M), isnan (3M), ldexp (3M), attributes (7), standards (7)