1 INTEGRATE
  Syntax: INTEGRATE nfun1 [nfun2...]
          xlo xhi
   where: nfun1,nfun2 are the function number(s) to integrate
          xlo         is the lower limit of the integration
          xhi         is the upper limit of the integration

  Integrates  one or  more  functions  over the  given range.  The default
  number  of intervals to sum  over is  100 and can be changed using
  the `SET FUNCTION INTEGRATE' command. If  you want  to  integrate all
  selected  functions, give the  function number 0. The  result is printed
  and is also  stored in register  101, which you can  use with the syntax
  `R101'.

