Article · Wikipedia archive · Last revised Jul 18, 2026

Summation equation

In mathematics, a summation equation or discrete integral equation is an equation in which an unknown function appears under a summation sign. The theories of summation equations and integral equations can be unified as integral equations on time scales using time scale calculus. A summation equation compares to a difference equation as an integral equation compares to a differential equation.

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In mathematics, a summation equation or discrete integral equation is an equation in which an unknown function appears under a summation sign. The theories of summation equations and integral equations can be unified as integral equations on time scales1 using time scale calculus. A summation equation compares to a difference equation as an integral equation compares to a differential equation.

The Volterra summation equation is: x ( t ) = f ( t ) + s = m n k ( t , s , x ( s ) ) {\displaystyle x(t)=f(t)+\sum _{s=m}^{n}k{\bigl (}t,s,x(s){\bigr )}} where x is the unknown function, s, t are integers, and f, k are known functions.

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