doubleint2

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mstyle displaystyle="true">
    <msubsup>
      <mo>&#x222C;</mo>
      <mn>0</mn>
      <mn>1</mn>
    </msubsup>
    <mi>f</mi>
    <mrow>
      <mo>(</mo>
      <mi>x</mi>
      <mo>)</mo>
    </mrow>
    <mtext>&#x200A;</mtext>
    <mo>&#x2146;</mo>
    <mi>x</mi>
  </mstyle>
</math>

Author: Design Science, Inc. (E. Cannon, E. Tabacman, R.Miner)