Split out the logarithm functions from the perplex exp(3). Also remove some
useless notes in the latter (namely, no one cares that financial calculations were done on Hewlett-Packard HP-71B, or that there is a LN1() in Pascal).
This commit is contained in:
jruoho
parent
a5f70e6aac
commit
6fd7775f29
@ -1,4 +1,4 @@
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# $NetBSD: Makefile,v 1.118 2011/08/06 11:01:12 jruoho Exp $
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# $NetBSD: Makefile,v 1.119 2011/09/13 05:26:47 jruoho Exp $
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#
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# @(#)Makefile 5.1beta 93/09/24
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#
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@ -210,7 +210,7 @@ MAN+= acos.3 acosh.3 asin.3 asinh.3 atan.3 atan2.3 atanh.3 \
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ceil.3 copysign.3 cos.3 cosh.3 \
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erf.3 exp.3 \
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fabs.3 finite.3 fmod.3 frexp.3 hypot.3 \
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ieee_test.3 ilogb.3 isinff.3 j0.3 ldexp.3 lgamma.3 lrint.3 \
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ieee_test.3 ilogb.3 isinff.3 j0.3 ldexp.3 lgamma.3 log.3 lrint.3 \
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math.3 modf.3 nextafter.3 \
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remainder.3 rint.3 round.3 \
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scalbn.3 sin.3 sinh.3 sqrt.3 \
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@ -246,11 +246,14 @@ MLINKS+=cosh.3 coshf.3
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MLINKS+=erf.3 erff.3 erf.3 erfc.3 erf.3 erfcf.3
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MLINKS+=exp.3 expf.3 exp.3 expm1.3 exp.3 expm1f.3 \
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exp.3 exp2.3 exp.3 exp2f.3 \
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exp.3 log.3 exp.3 logf.3 \
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exp.3 log10.3 exp.3 log10f.3 \
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exp.3 log1p.3 exp.3 log1pf.3 \
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exp.3 pow.3 exp.3 powf.3 \
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exp.3 log2.3 exp.3 log2f.3
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exp.3 pow.3 exp.3 powf.3
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MLINKS+=log.3 logf.3 \
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log.3 log10.3 \
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log.3 log10f.3 \
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log.3 log1p.3 \
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log.3 log1pf.3 \
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log.3 log2.3 \
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log.3 log2f.3
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MLINKS+=fabs.3 fabsf.3
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MLINKS+=finite.3 finitef.3
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MLINKS+=fmod.3 fmodf.3
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@ -27,9 +27,9 @@
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.\"
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.\" from: @(#)exp.3 6.12 (Berkeley) 7/31/91
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.\" $FreeBSD: src/lib/msun/man/exp.3,v 1.24 2008/01/18 21:43:00 das Exp $
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.\" $NetBSD: exp.3,v 1.26 2010/05/03 05:35:58 jruoho Exp $
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.\" $NetBSD: exp.3,v 1.27 2011/09/13 05:26:47 jruoho Exp $
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.\"
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.Dd May 3, 2010
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.Dd September 13, 2011
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.Dt EXP 3
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.Os
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.Sh NAME
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@ -41,17 +41,9 @@
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.\" .Nm exp2l ,
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.Nm expm1 ,
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.Nm expm1f ,
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.Nm log ,
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.Nm logf ,
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.Nm log2 ,
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.Nm log2f ,
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.Nm log10 ,
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.Nm log10f ,
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.Nm log1p ,
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.Nm log1pf ,
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.Nm pow ,
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.Nm powf
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.Nd exponential, logarithm, power functions
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.Nd exponential and power functions
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.Sh LIBRARY
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.Lb libm
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.Sh SYNOPSIS
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@ -71,22 +63,6 @@
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.Ft float
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.Fn expm1f "float x"
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.Ft double
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.Fn log "double x"
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.Ft float
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.Fn logf "float x"
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.Ft double
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.Fn log2 "double x"
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.Ft float
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.Fn log2f "float x"
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.Ft double
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.Fn log10 "double x"
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.Ft float
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.Fn log10f "float x"
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.Ft double
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.Fn log1p "double x"
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.Ft float
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.Fn log1pf "float x"
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.Ft double
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.Fn pow "double x" "double y"
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.Ft float
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.Fn powf "float x" "float y"
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@ -118,31 +94,6 @@ functions computes the value exp(x)\-1 accurately even for tiny argument
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.Fa x .
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.Pp
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The
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.Fn log
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function computes the value of the natural logarithm of argument
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.Fa x .
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.Pp
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The
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.Fn log10
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function computes the value of the logarithm of argument
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.Fa x
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to base 10.
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.Pp
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The
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.Fn log1p
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function computes
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the value of log(1+x) accurately even for tiny argument
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.Fa x .
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.Pp
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The
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.Fn log2
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and the
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.Fn log2f
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functions compute the value of the logarithm of argument
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.Fa x
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to base 2.
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.Pp
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The
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.Fn pow
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and
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.Fn powf
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@ -180,41 +131,15 @@ is set to
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and on the
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.Tn VAX
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generate a reserved operand fault.
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On a
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.Tn VAX ,
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.Va errno
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is set to
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.Er EDOM
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and the reserved operand is returned
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by log unless
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.Fa x
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\*[Gt] 0, by
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.Fn log1p
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unless
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.Fa x
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\*[Gt] \-1.
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.Sh ERRORS
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The values of
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.Fn exp x ,
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.Fn expm1 x ,
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.Fn exp2 x ,
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.Fn log x ,
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and
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.Fn log1p x ,
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.Fn exp2 x ,
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are exact provided that they are representable.
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Otherwise the error in these functions is generally below one
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.Em ulp .
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The values of
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.Fn log10 x
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are within about 2
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.Em ulps ;
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an
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.Em ulp
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is one
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.Em Unit
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in the
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.Em Last
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.Em Place .
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The error in
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.Fn pow x y
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is below about 2
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@ -248,36 +173,6 @@ is exact until it is bigger than 2**56 on a
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.Tn IEEE
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754.
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.Sh NOTES
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The functions
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.Fn exp x\ \-\ 1
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and
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.Fn log 1\ \+\ x
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are called
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.Fn expm1 x
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and
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.Fn logp1 x
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in
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.Tn BASIC
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on the Hewlett\-Packard
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.Tn HP Ns \-71B
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and
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.Tn APPLE
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Macintosh,
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.Tn EXP1
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and
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.Tn LN1
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in Pascal,
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.Fn exp1 x
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and
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.Fn log1 x
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in C
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on
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.Tn APPLE
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Macintoshes, where they have been provided to make
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sure financial calculations of ((1+x)**n\-1)/x, namely
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expm1(n*log1p(x))/x, will be accurate when x is tiny.
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They also provide accurate inverse hyperbolic functions.
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.Pp
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The function
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.Fn pow x 0
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returns x**0 = 1 for all x including x = 0,
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@ -340,9 +235,7 @@ and infinite x, i.e., independently of x.
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.Xr math 3
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.Sh STANDARDS
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The
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.Fn exp ,
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.Fn log ,
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.Fn log10
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.Fn exp
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and
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.Fn pow
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functions conform to
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@ -353,33 +246,19 @@ The
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.Fn expf ,
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.Fn expm1 ,
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.Fn expm1f ,
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.Fn log1p ,
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.Fn log1pf ,
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.Fn log2 ,
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.Fn log2f ,
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.Fn log10f ,
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.Fn logf ,
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and
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.Fn powf
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functions conform to
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.St -isoC-99 .
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.Sh HISTORY
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A
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.Fn exp ,
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.Fn log
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.Fn exp
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and
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.Fn pow
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functions
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appeared in
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.At v6 .
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A
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.Fn log10
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function
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appeared in
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.At v7 .
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The
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.Fn log1p
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and
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.Fn expm1
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functions appeared in
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function appeared in
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.Bx 4.3 .
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169
lib/libm/man/log.3
Normal file
169
lib/libm/man/log.3
Normal file
@ -0,0 +1,169 @@
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.\" $NetBSD: log.3,v 1.1 2011/09/13 05:26:47 jruoho Exp $
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.\"
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.\" Copyright (c) 2011 Jukka Ruohonen <jruohonen@iki.fi>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd September 13, 2011
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.Dt SCALBN 3
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.Os
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.Sh NAME
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.Nm log ,
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.Nm logf ,
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.Nm log10 ,
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.Nm log10f ,
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.Nm log1p ,
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.Nm log1pf
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.Nm log2 ,
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.Nm log2f ,
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.Nd logarithm functions
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.Sh LIBRARY
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.Lb libm
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.Sh SYNOPSIS
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.In math.h
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.Ft double
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.Fn log "double x"
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.Ft float
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.Fn logf "float x"
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.Ft double
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.Fn log10 "double x"
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.Ft float
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.Fn log10f "float x"
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.Ft double
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.Fn log1p "double x"
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.Ft float
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.Fn log1pf "float x"
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.Ft double
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.Fn log2 "double x"
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.Ft float
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.Fn log2f "float x"
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.Sh DESCRIPTION
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The following functions compute logarithms:
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.Bl -bullet -offset 2n
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.It
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The
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.Fn log
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and
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.Fn logf
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functions return the natural logarithm.
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.It
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The
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.Fn log10
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and
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.Fn log10f
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functions return the base 10 logarithm.
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.It
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The
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.Fn log1p
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and
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.Fn log1pf
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functions return the natural logarithm of (1.0 +
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.Fa x )
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accurately even for very small values of
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.Fa x .
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.It
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The
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.Fn log2
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and
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.Fn log2f
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functions return the base 2 logarithm.
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.Sh RETURN VALUES
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Upon successful completion, the functions return the logarithm of
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.Fa x
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as descibed above.
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Otherwise the following may occur:
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.Bl -enum -offset indent
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.It
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If
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.Fa x
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is \*(Na, all functions return \*(Na.
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.It
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If
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.Fa x
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is positive infinity, all functions return
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.Fa x .
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If
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.Fa x
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is negative infinity, all functions return \*(Na.
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.It
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If
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.Fa x
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is +0.0 or -0.0, the
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.Fn log ,
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.Fn log10 ,
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and
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.Fn log2
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families return either
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.Dv -HUGE_VAL ,
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.Dv -HUGE_VALF ,
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or
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.Dv -HUGE_VALL ,
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whereas the
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.Fn log1p
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family returns
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.Fa x .
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.It
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If
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.Fa x
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is +1.0, the
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.Fn log ,
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.Fn log10 ,
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and
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.Fn log2
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families return +0.0.
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If
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.Fa x
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is -1.0, the
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.Fn log1p
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family returns
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.Dv -HUGE_VAL ,
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.Dv -HUGE_VALF ,
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or
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.Dv -HUGE_VALL .
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.El
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.Pp
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In addition, on a
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.Tn VAX ,
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.Va errno
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is set to
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.Er EDOM
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and the reserved operand is returned
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by
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.Fn log
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unless
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.Fa x
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\*[Gt] 0, by
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.Fn log1p
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unless
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.Fa x
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\*[Gt] \-1.
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.Sh SEE ALSO
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.Xr exp 3 ,
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.Xr ilogb 3 ,
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.Xr math 3
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.Sh STANDARDS
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The described functions conform to
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.St -isoC-99 .
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.Sh HISTORY
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The history of the logarithm functions dates back to
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.At v6 .
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