subroutine in(j_dim,l_dim,td_dim,
     & j_max,l_max,c_x,c_y,x_max,y_max,courmx,no_out,t_out1)

c     Reads the data in input file adiprcon.in.

c     Writes to Fortran unit 1.  Uses Fortran unit 2 internally.

c     Avoid typos:
      implicit none

c Input variables:

c     Dimensioned mesh sizes in the x- and y-directions:
      integer j_dim,l_dim

c     Maximum tridiagonal system size:
      integer td_dim

c Output variables:

c     Actual mesh sizes in the x- and y-directions:
      integer j_max,l_max

c     Components of the convection velocity in the x and y directions:
      double precision c_x,c_y

c     Domain size in the x- and y-directions:
      double precision x_max,y_max

c     The largest of the two Courant numbers c_x dt / dx and c_y dt / dy:
      double precision courmx

c     Number of nonzero output times:
      integer no_out
c     First nonzero output time:
      double precision t_out1

c Local variables:

c     Constants, defined to simplify changing precision:
      double precision zero
      parameter (zero=0.d0)

c Executable statements:

c     Open the file:
      open(2,file='adiprcon.in',status='old')

c     Read the convection velocity in the x-direction:
      read(2,*)c_x
      write(1,110)c_x
 110  format('Convection velocity in the x-direction:',g15.7)
      if(c_x.le.zero)then
         print*,'*** adiprc: '//
     &   'The x-convection velocity must be positive, not',c_x
         stop
      endif

c     Read the convection velocity in the y-direction:
      read(2,*)c_y
      write(1,120)c_y
 120  format('Convection velocity in the y-direction:',g15.7)
      if(c_y.le.zero)then
         print*,'*** adiprc: '//
     &   'The y-convection velocity must be positive, not',c_y
         stop
      endif

c     Read the size of the domain in the x-direction:
      read(2,*)x_max
      write(1,130)x_max
 130  format('Size of the domain in the x-direction:',g15.7)
      if(x_max.le.zero)then
         print*,'*** adiprc: '//
     &   'The x-size must be positive but is',x_max
         stop
      endif

c     Read the size of the domain in the y-direction:
      read(2,*)y_max
      write(1,140)y_max
 140  format('Size of the domain in the y-direction:',g15.7)
      if(y_max.le.zero)then
         print*,'*** adiprc: '//
     &   'The y-size must be positive but is',y_max
         stop
      endif

c     Read the maximum Courant number:
      read(2,*)courmx
      write(1,150)courmx
 150  format('The maximum Courant number:',g15.7)
      if(courmx.le.zero)then
         print*,'*** adiprc: '//
     &   'The Courant number must be positive, not',courmx
         stop
      endif

c     Read the number of mesh segments to use in the x-direction:
      read(2,*)j_max
      write(1,160)j_max
 160  format('Number of mesh segments in the x-direction:',i4)
      if(j_max.lt.2)then
         print*,'*** adiprc: '//
     &   'The number of x-segments must be at least two but is',j_max
         stop
      endif
      if(j_max.gt.j_dim)then
         print*,'*** adiprc: '//
     &   'The requested number of x-segments,',j_max
         print*,'            '//
     &   'exceeds the maximum dimensioned limit',j_dim
         stop
      endif

c     Read the number of mesh points to use in the y-direction:
      read(2,*)l_max
      write(1,170)l_max
 170  format('Number of mesh segments in the y-direction:',i4)
      if(l_max.lt.2)then
         print*,'*** adiprc: '//
     &   'The number of y-segments must be at least two but is',l_max
         stop
      endif
      if(l_max.gt.l_dim)then
         print*,'*** adiprc: '//
     &   'The requested number of y-segments,',l_max
         print*,'            '//
     &   'exceeds the maximum dimensioned limit',l_dim
         stop
      endif

c     Check the tridiagonal system size:
      if(max(j_max,l_max).gt.td_dim)then
         print*,'*** adiprc: '//
     &   'The requested mesh dimensions,',j_max,l_max
         print*,'            '//
     &   'exceed the matrix storage limit',td_dim
         stop
      endif

c     Read the number of output times:
      read(2,*)no_out
      write(1,190)no_out
 190  format('Number of output times:',i4)
      if(no_out.le.0)then
         print*,'*** adiprc: '//
     &   'The number of output times must be positive, not',no_out
         stop
      endif

c     Read the first nonzero output time:
      read(2,*)t_out1
      write(1,200)t_out1
 200  format('First nonzero output time:',g15.7)
      if(no_out.lt.0.)then
         print*,'*** adiprc: '//
     &   'The first nonzero output time must be positive, not:',no_out
         stop
      endif

c     Close the input file:
      close(2)

      return
      end