boost_1_45_0/libs/math/doc/sf_and_dist/equations/special_functions_blurb18.mml

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <mtext>acosh</mtext>
    <mfenced>
      <mrow>
        <mi>x</mi>
      </mrow>
    </mfenced>
    <mspace width="1em"/>
    <mo>=</mo>
    <mspace width="1em"/>
    <mi>log</mi>
    <mfenced>
      <mrow>
        <mi>x</mi>
        <mo>+</mo>
        <msqrt>
          <mrow>
            <msup>
              <mi>x</mi>
              <mn>2</mn>
            </msup>
            <mo>&#x2212;</mo>
            <mn>1</mn>
          </mrow>
        </msqrt>
      </mrow>
    </mfenced>
  </mrow>
</math>