PROGRAM GEN_FLOW_ARROWS
C   This program takes the tmpout# files from the aml of the same name and 
C     does more calculations before generating the arrow coverages
      character*50 infile,outfile
      do 1 lay=1,6
         write (infile,fmt=’(a6,i1)’) ‘tmpout’,lay
         write (outfile,fmt=’(a5,i1)’) ‘genin’,lay
         
         open (unit=30,file=’check’)
         open (unit=10,file=infile)
         open (unit=20,file=outfile)
         write (outfile,’(a5,i1)’) ‘noout’,lay
         open (unit=25,file=outfile)
 10      read (10,*,end=98) ir,ic,iseq,x0,y0,xx,yy,slope
c   see if this is a large enough flux to worry about
         sum = abs(xx)+abs(yy)
         r=0
         angle=0
         if (sum .lt. 0.00001) then
c   if this cell got here it’s active, so we need to note it
            write (25,fmt=’(i10,2f15.4)’) iseq,x0,y0
            go to 10
         end if
c   Calculate the angle, then the x & y to get an arrow 420 cover units long
c     If xx is zero it’s just y, but we need it in the right direction
         if (xx .lt. 0.00001 .and. xx .gt.-0.00001) then
            y=420
            x=0
            if (yy .lt. 0.0) y=-420
c     Or if yy is zero it’s just x, but we need it in the right direction
         else if (yy .lt. 0.00001 .and. yy .gt.-0.00001) then
            y=0
            x=420
            if (xx .lt. 0.0) x=-420
c     Or if they are not zero then lets convert to polar coords. then use 
c       our arrow length for r.  Remember angle is in radians.
         else
c       get the angle and put it in the proper quadrant
            angle=atan(abs(slope))
            if (xx .lt. 0.0 .and. yy .gt. 0.0) 
     +         angle=3.141592654-angle
            if (xx .lt. 0.0 .and. yy .lt. 0.0) 
     +         angle=angle-3.141592654
            if (xx .gt. 0.0 .and. yy .lt. 0.0) 
     +         angle=0.0-angle
c       make the radius in the proper quandrant also
            r=420
            x=r*cos(angle)
            y=r*sin(angle)
         end if
c   Calc the arrow orig relative to x0 & y0, so the arrow goes through node
         xb=x0-(x/2)
         yb=y0-(y/2)
c   Calc the arrow point
         xe=x0+(x/2)
         ye=y0+(y/2)
c   Print out a file
         write (20,fmt=’(i10)’) iseq
         write (20,fmt=’(2f15.4)’) xb,yb
         write (20,fmt=’(2f15.4)’) xe,ye
         write (20,*) ‘END’
         if (lay .eq. 1)
     +     write (30,fmt=’(2i4,10f10.3)’),ir,ic,angle,r,x,y
         go to 10
 98      write (20,*) ‘END’
         write (25,*) ‘END’
         close (10)
         close (20)
         close (25)
 1    continue
      stop
      end