Date: Dec 4, 2012 4:09 AM
Author: Nick Broderick
Subject: Creating a Piecewise function with imported list of arbitrary length

Apologies if this seems like a simple question, but I'm not familiar enough with Mathematica syntax to know how to do this. Essentially I have an arbitrary list (length n) of pairs -- taken from an input file -- from which I need to define a Piecewise function. The pairs (x_i,y_i) define the left-sided endpoints for each portion of the function, and the last point defines the value y_n of the function for x > x_n. For example:

{{0,1},{300,2},{600,3}}

defines a Piecewise function:

f(x)= {{1, 0 <= x <300},{2, 300 <= x <600}, {3, x > 600}, {0, True}}

But I'm not sure how to go about creating a arbitrary list of conditions fr=
om my list of pairs. Any help would be appreciated.