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  12 .TH ldexp 3M "12 Jul 2006" "SunOS 5.11" "Mathematical Library Functions"
  13 .SH NAME
  14 ldexp, ldexpf, ldexpl \- load exponent of a floating point number
  15 .SH SYNOPSIS
  16 .LP
  17 .nf
  18 c99 [ \fIflag\fR... ] \fIfile\fR... \fB-lm\fR [ \fIlibrary\fR... ]
  19 #include <math.h>
  20 
  21 \fBdouble\fR \fBldexp\fR(\fBdouble\fR x, \fBint\fR exp);
  22 .fi
  23 
  24 .LP
  25 .nf
  26 \fBfloat\fR \fBldexpf\fR(\fBfloat\fR x, \fBint\fR exp);
  27 .fi
  28 
  29 .LP
  30 .nf
  31 \fBlong double\fR \fBldexpl\fR(\fBlong double\fR x, \fBint\fR exp);
  32 .fi
  33 
  34 .SH DESCRIPTION
  35 .sp
  36 .LP
  37 These functions computes the quantity x\|* 2^exp.
  38 .SH RETURN VALUES
  39 .sp
  40 .LP
  41 Upon successful completion, these functions return \fIx\fR multiplied by 2
  42 raised to the power \fIexp\fR.
  43 .sp
  44 .LP
  45 If these functions would cause overflow, a range error occurs and
  46 \fBldexp()\fR, \fBldexpf()\fR, and \fBldexpl()\fR return \fB\(+-HUGE_VAL\fR,
  47 \fB\(+-HUGE_VALF\fR, and \fB\(+-HUGE_VALL\fR (according to the sign of
  48 \fIx\fR), respectively.
  49 .sp
  50 .LP
  51 If \fIx\fR is NaN, a NaN is returned.
  52 .sp
  53 .LP
  54 If \fIx\fR is \(+-0 or \(+-Inf, \fIx\fR is returned.
  55 .sp
  56 .LP
  57 If \fIexp\fR  is 0, \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 is raised.
  74 .sp
  75 The \fBldexp()\fR function sets \fBerrno\fR to \fBERANGE\fR if the result
  76 overflows.
  77 .RE
  78 
  79 .SH USAGE
  80 .sp
  81 .LP
  82 An application wanting to check for exceptions should call
  83 \fBfeclearexcept\fR(\fBFE_ALL_EXCEPT\fR) before calling these functions. On
  84 return, if \fBfetestexcept\fR(\fBFE_INVALID\fR | \fBFE_DIVBYZERO\fR |
  85 \fBFE_OVERFLOW\fR | \fBFE_UNDERFLOW\fR) is non-zero, an exception has been
  86 raised. An application should either examine the return value or check the
  87 floating point exception flags to detect exceptions.
  88 .sp
  89 .LP
  90 An application can also set \fBerrno\fR to 0 before calling \fBldexp()\fR. On
  91 return, if \fBerrno\fR is non-zero, an error has occurred. The \fBldexpf()\fR
  92 and \fBldexpl()\fR functions do not set \fBerrno\fR.
  93 .SH ATTRIBUTES
  94 .sp
  95 .LP
  96 See \fBattributes\fR(5) for descriptions of the following attributes:
  97 .sp
  98 
  99 .sp
 100 .TS
 101 tab() box;
 102 cw(2.75i) |cw(2.75i) 
 103 lw(2.75i) |lw(2.75i) 
 104 .
 105 ATTRIBUTE TYPEATTRIBUTE VALUE
 106 _
 107 Interface StabilityStandard
 108 _
 109 MT-LevelMT-Safe
 110 .TE
 111 
 112 .SH SEE ALSO
 113 .sp
 114 .LP
 115 \fBfrexp\fR(3M), \fBisnan\fR(3M), \fBmodf\fR(3M), \fBattributes\fR(5),
 116 \fBstandards\fR(5)