1#!/usr/local/bin/ruby
2
3#
4# nlsolve.rb
5# An example for solving nonlinear algebraic equation system.
6#
7
8require "bigdecimal"
9require "bigdecimal/newton"
10include Newton
11
12class Function
13  def initialize()
14    @zero = BigDecimal::new("0.0")
15    @one  = BigDecimal::new("1.0")
16    @two  = BigDecimal::new("2.0")
17    @ten  = BigDecimal::new("10.0")
18    @eps  = BigDecimal::new("1.0e-16")
19  end
20  def zero;@zero;end
21  def one ;@one ;end
22  def two ;@two ;end
23  def ten ;@ten ;end
24  def eps ;@eps ;end
25  def values(x) # <= defines functions solved
26    f = []
27    f1 = x[0]*x[0] + x[1]*x[1] - @two # f1 = x**2 + y**2 - 2 => 0
28    f2 = x[0] - x[1]                  # f2 = x    - y        => 0
29    f <<= f1
30    f <<= f2
31    f
32  end
33end
34 f = BigDecimal::limit(100)
35 f = Function.new
36 x = [f.zero,f.zero]      # Initial values
37 n = nlsolve(f,x)
38 p x
39