fdisc.f.html CLAWPACK  
 Source file:   fdisc.f
 Directory:   /Users/rjl/git/rjleveque/clawpack-4.6.3/book/chap21/radialdam
 Converted:   Mon Jan 21 2013 at 20:15:39   using clawcode2html
 This documentation file will not reflect any later changes in the source file. 

 
c
c
c
c     =================================================
      function fdisc(x,y)
c     =================================================
      implicit double precision (a-h,o-z)
      common/cdisc/ x0,y0,alf,beta,r0,idisc
c
c     # for computing cell averages for initial data that has a
c     # discontinuity along some curve.  fdisc should be negative to the 
c     # left of the curve and positive to the right
c     # idisc specifies the nature of the discontinuity for two
c     # particular cases (a straight line and circle) but this routine
c     # can be modified for any other curve.
c
      go to (10,20) idisc
c
   10 continue
c     # straight line through (x0,y0) with normal (alf,beta) pointing 
c     # into right state
c
      fdisc = (x-x0)*alf + (y-y0)*beta
      return
c
   20 continue
c     # circle of radius r0:
      fdisc = (x-x0)**2 + (y-y0)**2 - r0**2
c
      return
      end