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<erlref>
  <header>
    <copyright>
      <year>1996</year>
      <year>2007</year>
      <holder>Ericsson AB, All Rights Reserved</holder>
    </copyright>
    <legalnotice>
  The contents of this file are subject to the Erlang Public License,
  Version 1.1, (the "License"); you may not use this file except in
  compliance with the License. You should have received a copy of the
  Erlang Public License along with this software. If not, it can be
  retrieved online at http://www.erlang.org/.

  Software distributed under the License is distributed on an "AS IS"
  basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
  the License for the specific language governing rights and limitations
  under the License.

  The Initial Developer of the Original Code is Ericsson AB.
    </legalnotice>

    <title>math</title>
    <prepared>Joe Armstrong</prepared>
    <responsible>Bjarne D&auml;cker</responsible>
    <docno>1</docno>
    <approved>Bjarne D&auml;cker</approved>
    <checked></checked>
    <date>97-01-15</date>
    <rev>B</rev>
    <file>math.sgml</file>
  </header>
  <module>math</module>
  <modulesummary>Mathematical Functions</modulesummary>
  <description>
    <p>This module provides an interface to a number of mathematical
      functions.</p>
    <note>
      <p>Not all functions are implemented on all platforms. In particular,
        the <c>erf/1</c> and <c>erfc/1</c> functions are not implemented on Windows.</p>
    </note>
  </description>
  <funcs>
    <func>
      <name>pi() -> float()</name>
      <fsummary>A useful number</fsummary>
      <desc>
        <p>A useful number.</p>
      </desc>
    </func>
    <func>
      <name>sin(X)</name>
      <name>cos(X)</name>
      <name>tan(X)</name>
      <name>asin(X)</name>
      <name>acos(X)</name>
      <name>atan(X)</name>
      <name>atan2(Y, X)</name>
      <name>sinh(X)</name>
      <name>cosh(X)</name>
      <name>tanh(X)</name>
      <name>asinh(X)</name>
      <name>acosh(X)</name>
      <name>atanh(X)</name>
      <name>exp(X)</name>
      <name>log(X)</name>
      <name>log10(X)</name>
      <name>pow(X, Y)</name>
      <name>sqrt(X)</name>
      <fsummary>Diverse math functions</fsummary>
      <type>
        <v>X = Y = number()</v>
      </type>
      <desc>
        <p>A collection of math functions which return floats. Arguments
          are numbers. </p>
      </desc>
    </func>
    <func>
      <name>erf(X) -> float()</name>
      <fsummary>Error function.</fsummary>
      <type>
        <v>X = number()</v>
      </type>
      <desc>
        <p>Returns the error function of <c>X</c>, where</p>
        <pre>
erf(X) = 2/sqrt(pi)*integral from 0 to X of exp(-t*t) dt.        </pre>
      </desc>
    </func>
    <func>
      <name>erfc(X) -> float()</name>
      <fsummary>Another error function</fsummary>
      <type>
        <v>X = number()</v>
      </type>
      <desc>
        <p><c>erfc(X)</c> returns  <c>1.0 - erf(X)</c>, computed  by
          methods that avoid cancellation for large <c>X</c>. </p>
      </desc>
    </func>
  </funcs>

  <section>
    <title>Bugs</title>
    <p>As these are the C library, the bugs are the same.</p>
  </section>
</erlref>

