% -*- texinfo -*-
% @deftypefn {Function File} {@var{y} =} lookup_table (@var{table}, @var{x})
% @deftypefnx {Function File} {@var{y} =} lookup_table (@var{table}, @var{x}, @var{interp}, @var{extrap})
% Using the lookup table created by @dfn{create_lookup_table}, find the value
% @var{y} corresponding to @var{x}. With two arguments the lookup is done
% to the nearest value below in the table less than the desired value. With
% three arguments a simple linear interpolation is performed. With four
% arguments an extrapolation is also performed. The exact values of arguments
% three and four are irrelevant, as only there presence detremines whether
% interpolation and/or extrapolation are used.
% @end deftypefn