FeynCalc manual (development version)

DeltaFunction

DeltaFunction[x] is the Dirac delta-function \delta (x).

Mathematica also provides a built-in function DiracDelta with comparable properties.

See also

Overview, Convolute, DeltaFunctionPrime, Integrate2, SimplifyDeltaFunction.

Examples

DeltaFunction[1 - x]

\delta (1-x)

Integrate2[DeltaFunction[1 - x] f[x], {x, 0, 1}]

f(1)

Integrate2[DeltaFunction[x] f[x], {x, 0, 1}]

f(0)

Integrate2[DeltaFunction[1 - x] f[x], {x, 0, 1}]

f(1)

Convolute[DeltaFunction[1 - x], x] /. FCGV[z_] :> ToExpression[z]

-x \delta (1-x) \log (x)