* This module contains several useful routines for interpolating
  data sets and finding where a given value lies in a sorted list.
  The first is a subroutine used to locate a position in an array
  of values where a given value would fit using bisection. It has
  been designed to be efficient in the common situation that it is
  called repeatedly. The user can supply a different set of comparison
  operators to replace the standard < and <=. For example, given a
  list (1, 2, 5, 8, 15) and the number 9.5 it would return 3.
* The remaining routines all are related to interpolating sets of
  (x,y) data pairs. They all take a list of (x,y) data pairs given
  another x value, return a sensible y value using the list of (x,y)
  data pairs. Three different interpolating functions are provided.
  The first, called a constant interpolator, assumes that the
  function being interpolated moves in non-linear jumps from one
  value to another. The interpolated value for some value x is the
  y value of the neighboring (x,y) to the left of the given x. The
  second interpolator performs a linear interpolation between the
  neighboring points. The third interpolator is called the robust
  interpolator and interpolates a smooth curve between all of the
  (x,y) pairs. To do the interpolation, it first calculates some
  reasonable derivatives at the (x,y) pairs. The robust interpolator
  can also use derivative information supplied by the user.

WWW: https://metacpan.org/release/Math-Interpolate