mirror of https://github.com/mkerrisk/man-pages
77 lines
1.6 KiB
Groff
77 lines
1.6 KiB
Groff
.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
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.\" and Copyright (C) 2011 Michael Kerrisk <mtk.manpages@gamil.com>
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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 CACOS 3 2011-09-15 "" "Linux Programmer's Manual"
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.SH NAME
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cacos, cacosf, cacosl \- complex arc cosine
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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 cacos(double complex " z );
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.br
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.BI "float complex cacosf(float complex " z );
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.br
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.BI "long double complex cacosl(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
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.BR cacos ()
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function calculates the complex arc cosine of
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.IR z .
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If \fIy\ =\ cacos(z)\fP, then \fIz\ =\ ccos(y)\fP.
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The real part of
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.I y
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is chosen in the interval [0,pi].
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.LP
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One has:
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.nf
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cacos(z) = \-i * clog(z + i * csqrt(1 \- z * z))
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.fi
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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 EXAMPLE
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.nf
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/* Link with "\-lm" */
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#include <complex.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <stdio.h>
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int
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main(int argc, char *argv[])
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{
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double complex z, c, f;
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double complex i = I;
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if (argc != 3) {
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fprintf(stderr, "Usage: %s <real> <imag>\\n", argv[0]);
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exit(EXIT_FAILURE);
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}
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z = atof(argv[1]) + atof(argv[2]) * I;
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c = cacos(z);
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printf("cacos() = %6.3f %6.3f*i\\n", creal(c), cimag(c));
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f = \-i * clog(z + i * csqrt(1 \- z * z));
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printf("formula = %6.3f %6.3f*i\\n", creal(f), cimag(f));
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exit(EXIT_SUCCESS);
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}
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.fi
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.SH SEE ALSO
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.BR ccos (3),
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.BR clog (3),
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.BR complex (7)
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