## Odds and Ends

### Creating Analytic Boundaries

Analytic Boundaries can only be created outside Grid3D. The coordinates of the boundary are calculated in a fortran program which is called by Grid or FeatFlow to get the coordinates for a given parameter value. The fortran program has to use exactly the method signatures from the code sample:

C calculates and returns the x coordinate based on the C given parameters: C T parameter value, must be DOUBLE PRECISION TO WORK! C must be in range [0,TMAX(IBCT)] C IBCT Number of boundary C I1,I2 utility integers (use for whatever you deem C neccessary) C D1,D2 utility doubles (use for whatever you deem C neccessary) DOUBLE PRECISION FUNCTION PARX(T,IBCT,I1,I2,D1,D2) IMPLICIT NONE DOUBLE PRECISION T INTEGER IBCT,I1,I2 DOUBLE PRECISION D1,D2 99998 END C C C C calculates and returns the y coordinate based on the C given parameters: C T parameter value, must be DOUBLE PRECISION TO WORK! C must be in range [0,TMAX(IBCT)] C IBCT Number of boundary C I1,I2 utility integers (use for whatever you deem C neccessary) C D1,D2 utility doubles (use for whatever you deem C neccessary) DOUBLE PRECISION FUNCTION PARY(T,IBCT,I1,I2,D1,D2) IMPLICIT NONE DOUBLE PRECISION T INTEGER IBCT,I1,I2 DOUBLE PRECISION D1,D2 PARY=T; 99999 END C C C C Returns the maximum parameter value for boundary number C IBCT. Must be DOUBLE PRECISIION TO WORK C DOUBLE PRECISION FUNCTION TMAX(IBCT) IMPLICIT NONE INTEGER IBCT TMAX=1D0; END

Note that the parameter interval is fixed at [0, TMAX(IBCT)] for each boundary. You can create several boundaries within the same file. To add this file to Grid use the browser.