qinit.f.html CLAWPACK  
 Source file:   qinit.f
 Directory:   /home/rjl/git/rjleveque/clawpack-4.x/doc/sphinx/example-acoustics-2d
 Converted:   Tue Jul 26 2011 at 12:46:10   using clawcode2html
 This documentation file will not reflect any later changes in the source file. 

 

c
c
c
c     =====================================================
       subroutine qinit(maxmx,maxmy,meqn,mbc,mx,my,xlower,ylower,
     &                   dx,dy,q,maux,aux)
c     =====================================================
c
c     # Set initial conditions for q.
c     # Acoustics with smooth radially symmetric profile to test accuracy
c
      implicit double precision (a-h,o-z)
      dimension q(1-mbc:maxmx+mbc, 1-mbc:maxmy+mbc, meqn)
      common /cwidth/ width
c
       pi = 4.d0*datan(1.d0)

       do 20 i=1,mx
          xcell = xlower + (i-0.5d0)*dx
          do 20 j=1,my
             ycell = ylower + (j-0.5d0)*dy
             r = dsqrt(xcell**2 + ycell**2)

             if (dabs(r-0.5d0) .le. width) then
                 pressure = 1.d0 + dcos(pi*(r - 0.5d0)/width)
               else
                 pressure = 0.d0
               endif
             q(i,j,1) = pressure
             q(i,j,2) = 0.d0
             q(i,j,3) = 0.d0
  20         continue
       return
       end