man3/finite.3

   1 .\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
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  23 .TH FINITE 3  2004-10-31 "" "Linux Programmer's Manual"
  24 .SH NAME
  25 finite, finitef, finitel, isinf, isinff, isinfl, isnan, isnanf, isnanl \-
  26 BSD floating point classification functions
  27 .SH SYNOPSIS
  28 .nf
  29 #define _BSD_SOURCE
  30 .br
  31 .B #include <math.h>
  32 .sp
  33 .BI "int finite(double " x );
  34 .br
  35 .BI "int finitef(float " x );
  36 .br
  37 .BI "int finitel(long double " x );
  38 .sp
  39 .BI "int isinf(double " x );
  40 .br
  41 .BI "int isinff(float " x );
  42 .br
  43 .BI "int isinfl(long double " x );
  44 .sp
  45 .BI "int isnan(double " x );
  46 .br
  47 .BI "int isnanf(float " x );
  48 .br
  49 .BI "int isnanl(long double " x );
  50 .fi
  51 .SH DESCRIPTION
  52 The
  53 .B finite
  54 functions return a non-zero value if \fIx\fP is neither infinite
  55 nor a "not-a-number" (NaN) value, and 0 otherwise.
  56
  57 The
  58 .B isnan
  59 functions return a non-zero value if \fIx\fP is a NaN value,
  60 and 0 otherwise.
  61
  62 The
  63 .B isinf
  64 functions return 1 if \fIx\fP is plus infinity, \-1 is \fIx\fP
  65 is minus infinity, and 0 otherwise.
  66
  67 .SH NOTE
  68 Note that these functions are obsolete. C99 defines macros
  69 isfinite(), isinf() and isnan() (for all types) replacing them.
  70 Further note that the C99 isinf() has weaker guarantees on the return value.
  71 See
  72 .BR fpclassify (3).
  73 .\"
  74 .\" finite* not on HP-UX; they exist on Tru64.
  75 .SH AVAILABILITY
  76 On a glibc system, these functions are declared by
  77 .I <math.h>
  78 when _BSD_SOURCE or _SVID_SOURCE or _GNU_SOURCE is defined.
  79 The isnan() functions will also be declared when _XOPEN_SOURCE
  80 is defined.
  81 .SH HISTORY
  82 The
  83 .B finite
  84 function occurs in BSD 4.3.
  85 .\" see IEEE.3 in the BSD 4.3 manual
  86 .SH "SEE ALSO"
  87 .BR fpclassify (3)