PHOTON USE
  x;  parxyz
 
  rot y ang 180
  gr x 1
  msg        EXPANDING - CONTRACTING GRID, Y-Z
  msg Press E to end
  enduse
#cls 
    GROUP 1. Run title and other preliminaries
TEXT( Expanding and contracting the grid
TITLE
LIBREF 
  DISPLAY
   In this example, PLANT is used for expanding and/or contracting 
   the Y-extent of the grid.
 
   It is useful in parabolic calculations; but it may be used more 
   generally.
 
   The PLANT statements headed by SCXS??  would perform a similar
   function for the X-direction domain width, XULAST, provided the 
   pointer AZXU is set to GRND.
    
    PLANT information :
     * Data input groups used:  4
     * Ground groups planted :  4
     * Headings used  : SCYS??
     * Functions used : None
     * Commands used  : REGION
  ENDDIS
 
REAL(POWER, HSLOT)
HSLOT=0.1
    GROUP 4. Y-direction grid specification
NY=20;YVLAST=HSLOT;YFRAC(1)=-20.;YFRAC(2)=1.0/20.
 
     ** Power law grid expansion and contraction
POWER=0.50;ZWADD=HSLOT
 
AZYV=GRND
NAMSAT=MOSG

        PLANTBEGIN
       YRAT=1.+:POWER:*DZ/(ZWADD+ZW)
      REGION(1,1,1,1) /IZ.LE.20
          YRAT=1.+:POWER:*(-1.)*DZ/(ZWADD+ZW)
         REGION(1,1,1,1) /IZ.GT.20.AND.IZ.LE.40
       YRAT=1.+:POWER:*1.*DZ/(ZWADD+ZW)
      REGION(1,1,1,1) /IZ.GT.40
       PLANTEND
  >>>>>>>>>>>>>>>>>>>>>> Comment begins >>>>>>>>>>>>>>>>>>>>
    The above three statements make the domain width a power
    law function of the downstream distance of  the  current
    slab  (ZW).  The  power  is  changed with Z-direction in
    step-wise manner.  It is positive over first  20  slabs,
    negative  over  next 20 slabs and positive again for the
    remainder of the domain.
  <<<<<<<<<<<<<<<<<<<<<<< Comment ends <<<<<<<<<<<<<<<<<<<<<
    GROUP 5. Z-direction grid specification
PARAB=T
    ** The z-direction step size is made proportional to YVLAST
       by setting AZDZ=PROPY and DZW1 here
NZ=100; AZDZ=PROPY; DZW1=0.05
    GROUP 7. Variables stored, solved & named
STORE(V1,W1)
LITHYD=1
     ** grid will be dumped in XYZ format file, PARXYZ.
TSTSWP=-1;IDISPA=5;IDISPB=1;IDISPC=NZ
dmpstk=t
DISTIL=T;store(prps,npor,epor)
EX(V1)=1.000E-10; EX(W1)=1.000E-10
 LIBREF=622
STOP