mirror of https://github.com/mkerrisk/man-pages
49 lines
1.0 KiB
Groff
49 lines
1.0 KiB
Groff
.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
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.\"
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.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
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.\" Distributed under GPL
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.\" %%%LICENSE_END
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.\"
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.TH CLOG 3 2008-08-11 "" "Linux Programmer's Manual"
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.SH NAME
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clog, clogf, clogl \- natural logarithm of a complex number
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.SH SYNOPSIS
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.B #include <complex.h>
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.sp
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.BI "double complex clog(double complex " z );
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.br
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.BI "float complex clogf(float complex " z );
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.br
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.BI "long double complex clogl(long double complex " z );
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.sp
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Link with \fI\-lm\fP.
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.SH DESCRIPTION
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The logarithm
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.BR clog ()
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is the inverse function of the exponential
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.BR cexp (3).
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Thus, if \fIy\ =\ clog(z)\fP, then \fIz\ =\ cexp(y)\fP.
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The imaginary part of
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.I y
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is chosen in the interval [\-pi,pi].
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.LP
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One has:
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.nf
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clog(z) = log(cabs(z)) + I * carg(z)
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.fi
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.LP
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Note that
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.I z
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close to zero will cause an overflow.
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.SH VERSIONS
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These functions first appeared in glibc in version 2.1.
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.SH CONFORMING TO
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C99.
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.SH SEE ALSO
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.BR cabs (3),
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.BR cexp (3),
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.BR clog10 (3),
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.BR clog2 (3),
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.BR complex (7)
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