From: Wolfgang Bangerth Date: Thu, 23 Jan 2020 17:11:55 +0000 (-0700) Subject: Improve an error message. X-Git-Tag: v9.2.0-rc1~616^2 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F9421%2Fhead;p=dealii.git Improve an error message. --- diff --git a/include/deal.II/numerics/derivative_approximation.h b/include/deal.II/numerics/derivative_approximation.h index be3854dd8c..bbe1450348 100644 --- a/include/deal.II/numerics/derivative_approximation.h +++ b/include/deal.II/numerics/derivative_approximation.h @@ -307,11 +307,16 @@ namespace DerivativeApproximation * Exception */ DeclExceptionMsg(ExcInsufficientDirections, - "We have encountered a cell on which the number of linearly " + "While computing a finite difference approximation to " + "derivatives, the algorithm encountered a cell on which " + "the number of linearly " "independent directions that span the matrix Y (discussed " "in the documentation of the DerivativeApproximation " "class) is not equal to dim. The matrix Y then is " - "rank deficient and can not be inverted."); + "rank deficient and can not be inverted. A common reason " + "why this might be happening is if a cell has neither " + "left/right (or up/down, or front/back) neighbors, for " + "example because the mesh is too coarse."); } // namespace DerivativeApproximation