<math display='block'> <mmlrow> <mmlsub> <mmli>a</mi> <mmli>v</mi> </msub> <mmlo>=</mo><mmlfrac> <mmln>1</mn> <mmli>m</mi> </mfrac> <mmlo>&#x22C5;</mo><mmlstyle displaystyle='true'> <mmlrow> <mmlsubsup> <mmlo>&#x222B;</mo> <mmln>0</mn> <mmli>t</mi> </msubsup> <mmlrow> <mmli>U</mi><mmlo stretchy='false'>(</mo><mmli>t</mi><mmlo stretchy='false'>)</mo><mmlo>&#x22C5;</mo><mmli>c</mi><mmlo stretchy='false'>(</mo><mmli>t</mi><mmlo stretchy='false'>)</mo><mmli>d</mi><mmli>t</mi> </mrow> </mrow> </mstyle> </mrow> </math>