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  12 .TH log10 3M "12 Jul 2006" "SunOS 5.11" "Mathematical Library Functions"
  13 .SH NAME
  14 log10, log10f, log10l \- base 10 logarithm function
  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 \fBlog10\fR(\fBdouble\fR \fIx\fR);
  22 .fi
  23 
  24 .LP
  25 .nf
  26 \fBfloat\fR \fBlog10f\fR(\fBfloat\fR \fIx\fR);
  27 .fi
  28 
  29 .LP
  30 .nf
  31 \fBlong double\fR \fBlog10l\fR(\fBlong double\fR \fIx\fR);
  32 .fi
  33 
  34 .SH DESCRIPTION
  35 .sp
  36 .LP
  37 These functions compute the base 10 logarithm of \fIx\fR, log(10)(\fIx\fR).
  38 .SH RETURN VALUES
  39 .sp
  40 .LP
  41 Upon successful completion, \fBlog10()\fR returns the base 10 logarithm of
  42 \fIx\fR.
  43 .sp
  44 .LP
  45 If \fIx\fR is \(+-0, a pole error occurs and \fBlog10()\fR, \fBlog10f()\fR, and
  46 \fBlog10l()\fR return \(mi\fBHUGE_VAL\fR, \(mi\fBHUGE_VALF\fR, and
  47 \(mi\fBHUGE_VALL\fR, respectively.
  48 .sp
  49 .LP
  50 For finite values of \fIx\fR that are less than 0, or if \fIx\fR is \(miInf, a
  51 domain error occurs and a NaN is returned.
  52 .sp
  53 .LP
  54 If \fIx\fR is NaN, a NaN is returned.
  55 .sp
  56 .LP
  57 If \fIx\fR is 1, +0 is returned.
  58 .sp
  59 .LP
  60 If \fIx\fR is +Inf, \fIx\fR is returned.
  61 .sp
  62 .LP
  63 For exceptional cases, \fBmatherr\fR(3M) tabulates the values to be returned by
  64 \fBlog10()\fR as specified by SVID3 and XPG3.
  65 .SH ERRORS
  66 .sp
  67 .LP
  68 These functions will fail if:
  69 .sp
  70 .ne 2
  71 .mk
  72 .na
  73 \fBDomain Error\fR
  74 .ad
  75 .RS 16n
  76 .rt  
  77 The finite value of \fIx\fR is negative, or \fIx\fR is -Inf.
  78 .sp
  79 If the integer expression (\fBmath_errhandling\fR & \fBMATH_ERREXCEPT\fR) is
  80 non-zero, the invalid floating-point exception is raised.
  81 .sp
  82 The \fBlog10()\fR function sets \fBerrno\fR to \fBEDOM\fR if the value of
  83 \fIx\fR is negative.
  84 .RE
  85 
  86 .sp
  87 .ne 2
  88 .mk
  89 .na
  90 \fBPole Error\fR
  91 .ad
  92 .RS 16n
  93 .rt  
  94 The value of \fIx\fR is 0.
  95 .sp
  96 If the integer expression (\fBmath_errhandling\fR & \fBMATH_ERREXCEPT\fR) is
  97 non-zero, the divide-by-zero floating-point exception is raised.
  98 .RE
  99 
 100 .SH USAGE
 101 .sp
 102 .LP
 103 An application wanting to check for exceptions should call
 104 \fBfeclearexcept\fR(\fBFE_ALL_EXCEPT\fR) before calling these functions. On
 105 return, if \fBfetestexcept\fR(\fBFE_INVALID\fR | \fBFE_DIVBYZERO\fR |
 106 \fBFE_OVERFLOW\fR | \fBFE_UNDERFLOW\fR) is non-zero, an exception has been
 107 raised. An application should either examine the return value or check the
 108 floating point exception flags to detect exceptions.
 109 .sp
 110 .LP
 111 An application can also set \fBerrno\fR to 0 before calling \fBlog10()\fR. On
 112 return, if \fBerrno\fR is non-zero, an error has occurred. The \fBlog10f()\fR
 113 and \fBlog10l()\fR functions do not set \fBerrno\fR.
 114 .SH ATTRIBUTES
 115 .sp
 116 .LP
 117 See \fBattributes\fR(5) for descriptions of the following attributes:
 118 .sp
 119 
 120 .sp
 121 .TS
 122 tab() box;
 123 cw(2.75i) |cw(2.75i) 
 124 lw(2.75i) |lw(2.75i) 
 125 .
 126 ATTRIBUTE TYPEATTRIBUTE VALUE
 127 _
 128 Interface StabilityStandard
 129 _
 130 MT-LevelMT-Safe
 131 .TE
 132 
 133 .SH SEE ALSO
 134 .sp
 135 .LP
 136 \fBfeclearexcept\fR(3M), \fBfetestexcept\fR(3M), \fBisnan\fR(3M),
 137 \fBlog\fR(3M), \fBmath.h\fR(3HEAD), \fBmatherr\fR(3M), \fBpow\fR(3M),
 138 \fBattributes\fR(5), \fBstandards\fR(5)