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  12 .TH isnan 3M "12 Jul 2006" "SunOS 5.11" "Mathematical Library Functions"
  13 .SH NAME
  14 isnan \- test for NaN
  15 .SH SYNOPSIS
  16 .LP
  17 .nf
  18 cc [ \fIflag\fR... ] \fIfile\fR... \fB-lm\fR [ \fIlibrary\fR... ]
  19 #include <math.h>
  20 
  21 \fBint\fR \fBisnan\fR(\fBdouble\fR \fIx\fR);
  22 .fi
  23 
  24 .LP
  25 .nf
  26 c99 [ \fIflag\fR... ] \fIfile\fR... \fB-lm\fR [ \fIlibrary\fR... ]
  27 #include <math.h>
  28 
  29 \fBint\fR \fBisnan\fR(\fBreal\(emfloating\fR \fIx\fR);
  30 .fi
  31 
  32 .SH DESCRIPTION
  33 .sp
  34 .LP
  35 In C90 mode, the \fBisnan()\fR function tests whether \fIx\fR is NaN.
  36 .sp
  37 .LP
  38 In C99 mode, the \fBisnan()\fR macro determines whether its argument value is
  39 NaN. First, an argument represented in a format wider than its semantic type is
  40 converted to its semantic type. The determination is then based on the type of
  41 the argument.
  42 .SH RETURN VALUES
  43 .sp
  44 .LP
  45 Both the \fBisnan()\fR function and macro return non-zero if and only if
  46 \fIx\fR is NaN.
  47 .SH ERRORS
  48 .sp
  49 .LP
  50 No errors are defined.
  51 .SH WARNINGS
  52 .sp
  53 .LP
  54 In C99 mode, the practice of explicitly supplying a prototype for \fBisnan()\fR
  55 after the line
  56 .sp
  57 .in +2
  58 .nf
  59 #include <math.h>
  60 .fi
  61 .in -2
  62 
  63 .sp
  64 .LP
  65 is obsolete and will no longer work.
  66 .SH ATTRIBUTES
  67 .sp
  68 .LP
  69 See \fBattributes\fR(5) for descriptions of the following attributes:
  70 .sp
  71 
  72 .sp
  73 .TS
  74 tab() box;
  75 cw(2.75i) |cw(2.75i) 
  76 lw(2.75i) |lw(2.75i) 
  77 .
  78 ATTRIBUTE TYPEATTRIBUTE VALUE
  79 _
  80 Interface StabilityStandard
  81 _
  82 MT-LevelMT-Safe
  83 .TE
  84 
  85 .SH SEE ALSO
  86 .sp
  87 .LP
  88 \fBfpclassify\fR(3M), \fBisfinite\fR(3M), \fBisinf\fR(3M), \fBisnormal\fR(3M),
  89 \fBmath.h\fR(3HEAD), \fBsignbit\fR(3M), \fBattributes\fR(5), \fBstandards\fR(5)