.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
.\"
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.\"
.TH FINITE 3  2021-03-22 "" "Linux Programmer's Manual"
.SH NAME
finite, finitef, finitel, isinf, isinff, isinfl, isnan, isnanf, isnanl \-
BSD floating-point classification functions
.SH SYNOPSIS
.nf
.B #include <math.h>
.PP
.BI "int finite(double " x );
.BI "int finitef(float " x );
.BI "int finitel(long double " x );
.PP
.BI "int isinf(double " x );
.BI "int isinff(float " x );
.BI "int isinfl(long double " x );
.PP
.BI "int isnan(double " x );
.BI "int isnanf(float " x );
.BI "int isnanl(long double " x );
.fi
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR finite (),
.BR finitef (),
.BR finitel ():
.nf
    /* Glibc since 2.19: */ _DEFAULT_SOURCE
        || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.PP
.BR isinf ():
    _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE
        || /* Glibc since 2.19: */ _DEFAULT_SOURCE
        || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.fi
.PP
.BR isinff (),
.BR isinfl ():
.nf
    /* Glibc since 2.19: */ _DEFAULT_SOURCE
        || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.fi
.PP
.BR isnan ():
.nf
    _XOPEN_SOURCE || _ISOC99_SOURCE
        || /* Glibc since 2.19: */ _DEFAULT_SOURCE
        || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.fi
.PP
.BR isnanf (),
.BR isnanl ():
.nf
    _XOPEN_SOURCE >= 600
        || /* Glibc since 2.19: */ _DEFAULT_SOURCE
        || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
.fi
.SH DESCRIPTION
The
.BR finite (),
.BR finitef (),
and
.BR finitel ()
functions return a nonzero value if
.I x
is neither infinite
nor a "not-a-number" (NaN) value, and 0 otherwise.
.PP
The
.BR isnan (),
.BR isnanf (),
and
.BR isnanl ()
functions return a nonzero value if
.I x
is a NaN value,
and 0 otherwise.
.PP
The
.BR isinf (),
.BR isinff (),
and
.BR isinfl ()
functions return 1 if
.I x
is positive infinity, \-1 if
.I x
is negative infinity, and 0 otherwise.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR finite (),
.BR finitef (),
.BR finitel (),
.BR isinf (),
.BR isinff (),
.BR isinfl (),
.BR isnan (),
.BR isnanf (),
.BR isnanl ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH NOTES
Note that these functions are obsolete.
C99 defines macros
.BR isfinite (),
.BR isinf (),
and
.BR isnan ()
(for all types) replacing them.
Further note that the C99
.BR isinf ()
has weaker guarantees on the return value.
See
.BR fpclassify (3).
.\"
.\" finite* not on HP-UX; they exist on Tru64.
.\" .SH HISTORY
.\" The
.\" .BR finite ()
.\" function occurs in 4.3BSD.
.\" see IEEE.3 in the 4.3BSD manual
.SH SEE ALSO
.BR fpclassify (3)