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  11 .TH exp2 3M "12 Jul 2006" "SunOS 5.11" "Mathematical Library Functions"
  12 .SH NAME
  13 exp2, exp2f, exp2l \- exponential base 2 functions
  14 .SH SYNOPSIS
  15 .LP
  16 .nf
  17 c99 [ \fIflag\fR... ] \fIfile\fR... \fB-lm\fR [ \fIlibrary\fR... ]
  18 #include <math.h>
  19 
  20 \fBdouble\fR \fBexp2\fR(\fBdouble\fR \fIx\fR);
  21 .fi
  22 
  23 .LP
  24 .nf
  25 \fBfloat\fR \fBexp2f\fR(\fBfloat\fR \fIx\fR);
  26 .fi
  27 
  28 .LP
  29 .nf
  30 \fBlong double\fR \fBexp2l\fR(\fBlong double\fR \fIx\fR);
  31 .fi
  32 
  33 .SH DESCRIPTION
  34 .sp
  35 .LP
  36 These functions compute the base-2 exponential of \fIx\fR.
  37 .SH RETURN VALUES
  38 .sp
  39 .LP
  40 Upon successful completion, these functions return 2^\fIx\fR.
  41 .sp
  42 .LP
  43 If the correct value would cause overflow, a range error occurs and
  44 \fBexp2()\fR, \fBexp2f()\fR, and \fBexp2l()\fR return the value of the macro
  45 \fBHUGE_VAL\fR, \fBHUGE_VALF\fR, and \fBHUGE_VALL\fR, respectively.
  46 .sp
  47 .LP
  48 If \fIx\fR is NaN, a NaN is returned.
  49 .sp
  50 .LP
  51 If \fIx\fR is \(+-0, 1 is returned.
  52 .sp
  53 .LP
  54 If \fIx\fR is \(miInf, +0 is returned.
  55 .sp
  56 .LP
  57 If \fIx\fR is +Inf, \fIx\fR is returned.
  58 .SH ERRORS
  59 .sp
  60 .LP
  61 These functions will fail if:
  62 .sp
  63 .ne 2
  64 .mk
  65 .na
  66 \fBRange Error\fR
  67 .ad
  68 .RS 15n
  69 .rt  
  70 The result overflows.
  71 .sp
  72 If the integer expression (\fBmath_errhandling\fR & \fBMATH_ERREXCEPT\fR) is
  73 non-zero, the overflow floating-point exception will be raised.
  74 .RE
  75 
  76 .SH USAGE
  77 .sp
  78 .LP
  79 An application wanting to check for exceptions should call
  80 \fBfeclearexcept\fR(\fBFE_ALL_EXCEPT\fR) before calling these functions. On
  81 return, if \fBfetestexcept\fR(\fBFE_INVALID\fR | \fBFE_DIVBYZERO\fR |
  82 \fBFE_OVERFLOW\fR | \fBFE_UNDERFLOW\fR) is non-zero, an exception has been
  83 raised. An application should either examine the return value or check the
  84 floating point exception flags to detect exceptions.
  85 .SH ATTRIBUTES
  86 .sp
  87 .LP
  88 See \fBattributes\fR(5) for descriptions of the following attributes:
  89 .sp
  90 
  91 .sp
  92 .TS
  93 tab() box;
  94 cw(2.75i) |cw(2.75i) 
  95 lw(2.75i) |lw(2.75i) 
  96 .
  97 ATTRIBUTE TYPEATTRIBUTE VALUE
  98 _
  99 Interface StabilityStandard
 100 _
 101 MT-LevelMT-Safe
 102 .TE
 103 
 104 .SH SEE ALSO
 105 .sp
 106 .LP
 107 \fBexp\fR(3M), \fBfeclearexcept\fR(3M), \fBfetestexcept\fR(3M),
 108 \fBisnan\fR(3M), \fBlog\fR(3M), \fBmath.h\fR(3HEAD), \fBattributes\fR(5),
 109 \fBstandards\fR(5)