This document contains the problems for the Group Homework Assignment
for Tuesday, February 24.

The problems are from Strogatz, Chapter 3.  The assignment is to 
program the system (one ODE in this case) and use XPP to find
the bifurcation diagram.

Problem 3-1-2:
  x' = r - cosh x

Problem 3-2-1:
  x' = rx + x^2

Problem 3-2-2:
  x' = rx - ln(1+x)

Problem 3-4-1:
  x' = rx + 4x^3

Problem 3-4-7:
  x' = 5 - r exp(-x^2)