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1.5.7 Limitations and bugs

• Files that can be created by the system
  If xx is the name given by the user, the file names that can be created from xx are:

  traceNNN.emc2_trace	Trace of operations (automatically generated names).
  xx.emc2_trace	Trace of operations (name given by the user).
  xx.emc2_bd	Save under CONSTRUCTION or under PREP MESH
  xx_bak.emc2_bd	.bak file of the previous one.
  xx.data	File for the APNOPO module (it will generate xx.nopo).
  xx.nopo	File generated by EDIT MESH.
  xx.mesh	File generated by EDIT MESH.
  xx.am	File generated by EDIT MESH.
  xx.am_fmt	File generated by EDIT MESH.
  xx.ambda	File generated by EDIT MESH.
  xx.set	For linking with the VISIL software.
  xx.bas	For linking with the VISIL software.

• Initialization of global variables
  Maximum number of
  • DB elements MXBDX=10000
  • discretization points on a DB element MXNOD=2000
  • points defining a spline MXPDEF=200
  • vertices in a mesh MBPMXX=50000
  • triangles in a mesh NBTMXX=2*NBPMXX-2=99998
  • edges that define the boundaries in a mesh NBAMXX=10000
  • subdomains MBSDMXX=2000
  • list elements MXLISTX=50000

  All those variables are initialized by program emc2.f (directory ppal), except MXNOD and MXPDEF, which are initialized in include file emc2_commons_g.ins in directory include.

• We must be careful when several DB elements are superimposed, for example a segment and its supporting line, when the selection mode is ANY: the result of the selection is unpredictable.
• When switching from the CONSTRUCTION  application to the
  [4] PREP_MESH application, if two arcs, segments or splines are superimposed, one of them is destroyed.
• If the mesh generator, which is called when switching to the
  [4] EDIT_MESH  application, refuses to construct the mesh, the reason is in all probability that:
  • all segments, arcs and splines must be cut explicitly i.e. an extremity of a segment, arc or spline cannot lie on a curve that is not cut.
  • when we construct arcs with properties of tangency, we can encounter rounding off error problems. To avoid this, we must construct the points of tangency first and then use them.
  • the precision of the mesh generator is 1/32000 with respect to the larger length. If we ask for a too fine discretization, the mesh generator can either turn triangles over or refuse to mesh, because some points are considered equal. 
  • a curve is not discretized enough: the boundary is (self?) crossed .
  the type of error is: some points are considered equal or the boundary is (self?) crossed (or crosses itself?)
• Generally, the mesh generator will not conserve the symmetries of the domain. If we want to keep these symmetries, we must first mesh the minimal part, then generate the entire mesh by using the transformations of the EDIT_MESH  application.
• Warning: using transformations of the EDIT_MESH application may result in the construction of overlapping subdomains. The results are unpredictable.
• Warning: the mesh points that are read by the EDIT_MESH application are not appended to the points of already existing meshes.
• Warning: all the modifications of a mesh are lost when exiting the EDIT_MESH application. The mesh is lost and only the contours are saved.
• Warning: because of a fortran problem (INQUIRE), it is impossible   to execute emc2 in a write protected directory (the programme attempts to open 999 LOG FILE files, see 1.5.2, which takes some time)
• If you lose information in the graphic window, the only way to refresh it is to resize it and then click inside.