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<erlref>
  <header>
    <copyright>
      <year>1996</year>
      <year>2020</year>
      <holder>Ericsson AB, All Rights Reserved</holder>
    </copyright>
    <legalnotice>
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
 
      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions 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>1997-01-15</date>
    <rev>B</rev>
    <file>math.xml</file>
  </header>
  <module since="">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 provided on all platforms. In particular,
        the <seemfa marker="#erf/1"><c>erf/1</c></seemfa> and
        <seemfa marker="#erfc/1"><c>erfc/1</c></seemfa> functions
        are not provided on Windows.</p>
    </note>
  </description>

  <funcs>
    <func>
      <name name="acos" arity="1" since=""/>
      <name name="acosh" arity="1" since=""/>
      <name name="asin" arity="1" since=""/>
      <name name="asinh" arity="1" since=""/>
      <name name="atan" arity="1" since=""/>
      <name name="atan2" arity="2" since=""/>
      <name name="atanh" arity="1" since=""/>
      <name name="ceil" arity="1" since="OTP 20.0"/>
      <name name="cos" arity="1" since=""/>
      <name name="cosh" arity="1" since=""/>
      <name name="exp" arity="1" since=""/>
      <name name="floor" arity="1" since="OTP 20.0"/>
      <name name="fmod" arity="2" since="OTP 20.0"/>
      <name name="log" arity="1" since=""/>
      <name name="log10" arity="1" since=""/>
      <name name="log2" arity="1" since="OTP 18.0"/>
      <name name="pow" arity="2" since=""/>
      <name name="sin" arity="1" since=""/>
      <name name="sinh" arity="1" since=""/>
      <name name="sqrt" arity="1" since=""/>
      <name name="tan" arity="1" since=""/>
      <name name="tanh" arity="1" since=""/>
      <fsummary>Diverse math functions.</fsummary>
      <type variable="X" name_i="6"/>
      <type variable="Y" name_i="6"/>
      <desc>
        <p>A collection of mathematical functions that return floats. Arguments
          are numbers.</p>
      </desc>
    </func>

    <func>
      <name name="erf" arity="1" since=""/>
      <fsummary>Error function.</fsummary>
      <desc>
        <p>Returns the error function of <c><anno>X</anno></c>, where:</p>
        <pre>
erf(X) = 2/sqrt(pi)*integral from 0 to X of exp(-t*t) dt.</pre>
      </desc>
    </func>

    <func>
      <name name="erfc" arity="1" since=""/>
      <fsummary>Another error function.</fsummary>
      <desc>
        <p><c>erfc(X)</c> returns <c>1.0</c> - <c>erf(X)</c>, computed by
          methods that avoid cancellation for large <c><anno>X</anno></c>.</p>
      </desc>
    </func>

    <func>
      <name name="pi" arity="0" since=""/>
      <fsummary>A useful number.</fsummary>
      <desc>
        <p>A useful number.</p>
      </desc>
    </func>

  </funcs>

  <section>
    <title>Limitations</title>
    <p>As these are the C library, the same limitations apply.</p>
  </section>
</erlref>

