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diff --git a/jni/ruby/ext/bigdecimal/sample/nlsolve.rb b/jni/ruby/ext/bigdecimal/sample/nlsolve.rb
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+++ b/jni/ruby/ext/bigdecimal/sample/nlsolve.rb
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+#!/usr/local/bin/ruby
+
+#
+# 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.new("0.0")
+    @one  = BigDecimal.new("1.0")
+    @two  = BigDecimal.new("2.0")
+    @ten  = BigDecimal.new("10.0")
+    @eps  = BigDecimal.new("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