subroutine linint(x,y)
c
c     Given a value of x return a value of y based on interpolation
c     within a table of y values (ytab) corresponding to the x values
c     contained in the array xtab.  The subroutine assumes that the
c     values in xtab increase monotonically
c
c    John Mahaffy 2/12/95
c
      real xtab(11),ytab(11)
      data ytab/1.0,2.1,3.2,4.4,5.7,7.1,8.6,10.2,11.9,13.7,15.8/
      data xtab
     & /300.,400.,500.,600.,700.,800.,900.,1000.,1100.,1200.,1300./
      if (x.lt.xtab(1).or.x.gt.xtab(11)) then
         write(6,*) 'x = ', x, '  is out of table range'
         stop
      endif
      do 100 i=2,11
         if (x.le.xtab(i)) go to 200
  100    continue
  200 i1=i-1
      wx=(x-xtab(i1))/(xtab(i1+1)-xtab(i1))
      y=(1-wx)*ytab(i1)+wx*ytab(i1+1)
      return
      end