# Metadata | Property | Value | | -------- | ----- | | Reported by | Carsten Gräser (graeser@math.fu-berlin.de) | | Reported at | Mar 25, 2013 20:27 | | Type | Bug Report | | Version | Git (pre2.4) [autotools] | | Operating System | Unspecified / All | # Description If you insert a BoundarySegment with a parametrization into an AluGrid (simplex,2d) and refine it several times the local coordinates used in the parametrization are not uniformly distributed on the unit interval. If you refine the grid n times, one would expect, that the parametrization is evaluated at i/n for values of i in {0,1,2,...,n}. In fact the local coordinates differ from this with increasing error for more refinement levels. This leads to distorted triangles at the boundary even for a perfect parametrization. The attached example demonstrates this for a quarter arc of the unit circle. For 1,..,3 refinement levels (passed as command line argument) the grid looks OK. For 4 refinements one can see that the boundary faces do not have the same length. For 6 refinements there are even overlapping boundary elements. This behaviour seems not to happen, if the BoundarySegment just interpolates between its vertices, so it is dependent on the actual parametrization function. # Attachments * [test_alu_parametrization.cc](/uploads/0d223db50455e911d505f4ff5e60581d/test_alu_parametrization.cc)