[Getdp] Bug in GetDP

tptrsn at ksu.edu tptrsn at ksu.edu
Tue Feb 12 23:40:44 CET 2008


Hello,

while working with GetDP, my major professor found this bug in GetDP.  I
am wondering if anyone has explanation of this.

Attached are .geo and .pro filed of the two cases.  In each they are the
same cube geometry with a simple electrostatics case of a fixed voltage
on one surface and a Neumann boundary condition specifying grad V on
the opposing surface.

In the file appropriately named -works, the side of the cube
corresponding to the +z face is set to a voltage and the -z face is set
to grad v = -5.

This solution runs and provides the expected results of a linear
gradient of voltage throughout the cube.

The file named -fails is the exact same problem as the previous example,
but the surfaces for the boundary conditions have been shifted to the
opposing faces named the Sright and Sleft.  In this case the program
returns the following error:

GetDP   : Error     : Null determinant in 'Get_InverseMatrix'

By symmetry this is the same problem, we have just turned the cube on
one side, yet the solution fails and returns the same error message. 
the combination of the other sides also returns the error message.


Sincerely,
Todd Petersen
Kansas State University

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