#!/usr/local/bin/ruby
# frozen_string_literal: false
#
# nlsolve.rb
# An example for solving nonlinear algebraic equation system.
#
require "bigdecimal"
require "bigdecimal/newton"
include Newton
class Function # :nodoc: all
def initialize()
@zero = BigDecimal("0.0")
@one = BigDecimal("1.0")
@two = BigDecimal("2.0")
@ten = BigDecimal("10.0")
@eps = BigDecimal("1.0e-16")
end
def zero;@zero;end
def one ;@one ;end
def two ;@two ;end
def ten ;@ten ;end
def eps ;@eps ;end
def values(x) # <= defines functions solved
f = []
f1 = x[0]*x[0] + x[1]*x[1] - @two # f1 = x**2 + y**2 - 2 => 0
f2 = x[0] - x[1] # f2 = x - y => 0
f <<= f1
f <<= f2
f
end
end
f = BigDecimal.limit(100)
f = Function.new
x = [f.zero,f.zero] # Initial values
n = nlsolve(f,x)
p x
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