significand, significandf, significandl — get mantissa of floating-point number


#include <math.h>

double significand(double x);
float significandf(float x);
long double significandl(long double x);

Link with -lm.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

significand(), significandf(), significandl():

/* Since glibc 2.19: */ _DEFAULT_SOURCE
   || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE


These functions return the mantissa of x scaled to the range [1,2). They are equivalent to

scalb(x, (double) -ilogb(x))

This function exists mainly for use in certain standardized tests for IEEE 754 conformance.


For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
Thread safety MT-Safe

Conforming to

These functions are nonstandard; the double version is available on a number of other systems.

See Also

ilogb(3), scalb(3)


This page is part of release 5.04 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at

Referenced By


The man pages significandf(3) and significandl(3) are aliases of significand(3).

2017-09-15 GNU Linux Programmer's Manual