7
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Bug persists through V13.0.0 or later

Here is a basic example found in the documentation of GreenFunction:

reg = Rectangle[{0, 0}, {1, 1}];
GreenFunction[
   {Laplacian[v[x, y], {x, y}] + v[x, y], 
    DirichletCondition[v[x, y] == 0, True]},
   v, Element[{x, y}, reg], {ξ, η}
]

(* Function[{x, y, ξ, η}, -4 Inactive[Sum][(Sin[π x K[1]] Sin[π ξ K[1]] Sin[π y K[2]] Sin[π η K[2]])/(-1 + π^2 K[1]^2 + π^2 K[2]^2), {K[1], 1, ∞}, {K[2], 1, ∞}]] *)

The above evaluates symbolically as expected.

But if I shift the region:

reg = Rectangle[{-1/2, -1/2}, {1/2, 1/2}]
GreenFunction[
   {Laplacian[v[x, y], {x, y}] + v[x, y], 
    DirichletCondition[v[x, y] == 0, True]},
   v, Element[{x, y}, reg], {ξ, η}
]

then GreenFunction no longer evaluates and returns the input!

What could be the reason ? Is there a workaround?

Improve this question
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7
  • $\begingroup$ I think this is reportable to Support. A related question. $\endgroup$
    – J. M.'s missing motivation ♦
    Commented Dec 11, 2021 at 15:43
  • $\begingroup$ Thank you for your answer: What is the correct way to contact mathematica support? Thanks! $\endgroup$
    – Ulrich Neumann
    Commented Dec 11, 2021 at 15:48
  • $\begingroup$ Send them a message here. $\endgroup$
    – J. M.'s missing motivation ♦
    Commented Dec 11, 2021 at 15:58
  • 1
    $\begingroup$ This seems to fall under the bugs category $\endgroup$
    – polfosol
    Commented Dec 11, 2021 at 16:01
  • $\begingroup$ @J. M. Thank you, I'll contact Wolfram! $\endgroup$
    – Ulrich Neumann
    Commented Dec 11, 2021 at 17:31

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