157 lines
4.2 KiB
HTML
157 lines
4.2 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of CACOS</TITLE>
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</HEAD><BODY>
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<H1>CACOS</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2019-03-06<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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cacos, cacosf, cacosl - complex arc cosine
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>#include <<A HREF="file:///usr/include/complex.h">complex.h</A>></B>
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<P>
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<B>double complex cacos(double complex </B><I>z</I><B>);</B>
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<BR>
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<B>float complex cacosf(float complex </B><I>z</I><B>);</B>
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<BR>
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<B>long double complex cacosl(long double complex </B><I>z</I><B>);</B>
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<P>
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Link with <I>-lm</I>.
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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These functions calculate the complex arc cosine of
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<I>z</I>.
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If <I>y = cacos(z)</I>, then <I>z = ccos(y)</I>.
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The real part of
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<I>y</I>
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is chosen in the interval [0,pi].
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<P>
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One has:
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<P>
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<PRE>
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cacos(z) = -i * clog(z + i * csqrt(1 - z * z))
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</PRE>
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<A NAME="lbAE"> </A>
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<H2>VERSIONS</H2>
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These functions first appeared in glibc in version 2.1.
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<A NAME="lbAF"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>cacos</B>(),
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<B>cacosf</B>(),
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<B>cacosl</B>()
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</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
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</TABLE>
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<A NAME="lbAG"> </A>
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<H2>CONFORMING TO</H2>
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C99, POSIX.1-2001, POSIX.1-2008.
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<A NAME="lbAH"> </A>
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<H2>EXAMPLE</H2>
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/* Link with "-lm" */
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<P>
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#include <<A HREF="file:///usr/include/complex.h">complex.h</A>>
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#include <<A HREF="file:///usr/include/stdlib.h">stdlib.h</A>>
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#include <<A HREF="file:///usr/include/unistd.h">unistd.h</A>>
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#include <<A HREF="file:///usr/include/stdio.h">stdio.h</A>>
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<P>
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int
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main(int argc, char *argv[])
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{
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<BR> double complex z, c, f;
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<BR> double complex i = I;
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<P>
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<BR> if (argc != 3) {
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<BR> fprintf(stderr, "Usage: %s <real> <imag>\n", argv[0]);
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<BR> exit(EXIT_FAILURE);
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<BR> }
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<P>
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<BR> z = atof(argv[1]) + atof(argv[2]) * I;
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<P>
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<BR> c = cacos(z);
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<P>
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<BR> printf("cacos() = %6.3f %6.3f*i\n", creal(c), cimag(c));
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<P>
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<BR> f = -i * clog(z + i * csqrt(1 - z * z));
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<P>
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<BR> printf("formula = %6.3f %6.3f*i\n", creal(f), cimag(f));
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<P>
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<BR> exit(EXIT_SUCCESS);
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}
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<A NAME="lbAI"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+ccos">ccos</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+clog">clog</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?7+complex">complex</A></B>(7)
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<A NAME="lbAJ"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="1"><A HREF="#lbAB">NAME</A><DD>
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<DT id="2"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="3"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="4"><A HREF="#lbAE">VERSIONS</A><DD>
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<DT id="5"><A HREF="#lbAF">ATTRIBUTES</A><DD>
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<DT id="6"><A HREF="#lbAG">CONFORMING TO</A><DD>
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<DT id="7"><A HREF="#lbAH">EXAMPLE</A><DD>
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<DT id="8"><A HREF="#lbAI">SEE ALSO</A><DD>
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<DT id="9"><A HREF="#lbAJ">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:37 GMT, March 31, 2021
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