protected override IGrid CreateOrLoadGrid() { GridCommons grd; switch (TestCase) { case 1: { // ++++++++++++++++++ // affine-linear mesh // ++++++++++++++++++ double[] xNodes = GenericBlas.Linspace(-5, 5, 21); double[] yNodes = GenericBlas.Linspace(-5, 5, 21); grd = Grid2D.Cartesian2DGrid(xNodes, yNodes); break; } case 2: { // +++++++++++ // curved mesh // +++++++++++ double[] xNodes = GenericBlas.Linspace(-5, 5, 21); double[] yNodes = GenericBlas.Linspace(-5, 5, 21); grd = Grid2D.BilinearSquareGrid(xNodes, yNodes, factor: 0.8); break; } default: throw new ArgumentException("unknown test-case index"); } return(grd); }