# inverse – Special result of InverseHankelTransform

Hmmm. I'm not 100% sure because I'm not familiar with Hankel transformations. But I read that in the documents `HankelTransform` implicitly assumes that the input function is supported in $$]0, infty[[[[$$, So if `ring delta` is not zero, `r0` must be positive As I said, this is implicitly accepted; for the return value of `InverseHankelTransform`this is explicitly stated by multiplication `HeavisideTheta[r0]`, Also note that
`1 / (2πr) DiracDelta[r - r0]` equal `1 / (2πr0) DiracDelta[r - r0]`,

We can check the result `InverseHankelTransform` equal `ring delta` in the sense of distribution by integration against a symbolic test function:

``````Integrate[(ringDelta - InverseHankelTransform[fRingDelta, ρ, r]) φ[r],
{r, 0, ∞},
Assumptions -> r0> 0
]
``````

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