qinit.f.html CLAWPACK  
 Source file:   qinit.f
 Directory:   /Users/rjl/git/clawpack/apps/fvmbook/chap20/rotate
 Converted:   Wed Jan 4 2017 at 21:04:32   using clawcode2html
 This documentation file will not reflect any later changes in the source file. 

 

c
c
c
c     =====================================================
       subroutine qinit(meqn,mbc,mx,my,xlower,ylower,
     &                   dx,dy,q)
c     =====================================================
c
c     # Set initial conditions for q.
c     # Sample scalar equation with data that is piecewise constant with
c     # q = 1.0  if  0.2 < x < 0.6   and   0.2 < y < 0.6
c     #     0.0  otherwise
c
       implicit double precision (a-h,o-z)
       dimension q(meqn,1-mbc:mx+mbc,1-mbc:my+mbc)
c
       do 20 i=1,mx
	  xi = xlower + (i-0.5d0)*dx
          do 20 j=1,my
	     yj = ylower + (j-0.5d0)*dy
 	     if (xi.lt.0.6d0 .and. xi.gt.0.1d0 .and. yj.gt.-0.25d0 .and.
     &		 yj.lt.0.25d0) then
		     q(1,i,j) = 1.d0
		   else
		     q(1,i,j) = 0.d0
		   endif
	     r = dsqrt((xi+0.45d0)**2 + yj**2)
	     if (r .lt. 0.35d0) then
	         q(1,i,j) = 1.d0 - r/0.35d0
		 endif

  20         continue
       return
       end