Dir. rearrangement according to the suggestions from Minero Aoki.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@3722 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/bigdecimal/sample/linear.rb

@@ -0,0 +1,46 @@
+#!/usr/local/bin/ruby
+
+#
+# linear.rb
+#
+# Solves linear equation system(A*x = b) by LU decomposition method.
+#  where  A is a coefficient matrix,x is an answer vector,b is a constant vector.
+#
+require "bigdecimal"
+require "ludcmp"
+
+include LUSolve
+
+def rd_order
+   printf("Number of equations ?")
+   n = gets().chomp.to_i
+end
+
+zero = BigDecimal::new("0.0")
+one  = BigDecimal::new("1.0")
+
+while (n=rd_order())>0
+  a = []
+  as= []
+  b = []
+  printf("\nEnter coefficient matrix element A[i,j]\n");
+  for i in 0...n do
+    for j in 0...n do
+      printf("A[%d,%d]? ",i,j); s = gets
+      a <<=BigDecimal::new(s);
+      as<<=BigDecimal::new(s);
+    end
+    printf("Contatant vector element b[%d] ? ",i);b<<=BigDecimal::new(gets);
+  end
+  printf "ANS="
+  x = lusolve(a,b,ludecomp(a,n,zero,one),zero)
+  p x
+  printf "A*x-b\n"
+  for i in 0...n do
+    s = zero
+    for j in 0...n do
+       s = s + as[i*n+j]*x[j]
+    end
+    p s-b[i]
+  end
+end

ext/bigdecimal/sample/nlsolve.rb

@@ -0,0 +1,38 @@
+#!/usr/local/bin/ruby
+
+#
+# nlsolve.rb
+# An example for solving nonlinear algebraic equation system.
+#
+
+require "bigdecimal"
+require "newton"
+include Newton
+
+class Function
+  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

ext/bigdecimal/sample/pi.rb

@@ -0,0 +1,50 @@
+#!/usr/local/bin/ruby
+
+#
+# pi.rb
+#
+
+require "bigdecimal"
+#
+# Calculates 3.1415.... (the number of times that a circle's diameter
+# will fit around the circle) using J. Machin's formula.
+#
+def big_pi(sig) # sig: Number of significant figures
+  exp    = -sig
+  pi     = BigDecimal::new("0")
+  two    = BigDecimal::new("2")
+  m25    = BigDecimal::new("-0.04")
+  m57121 = BigDecimal::new("-57121")
+
+  u = BigDecimal::new("1")
+  k = BigDecimal::new("1")
+  w = BigDecimal::new("1")
+  t = BigDecimal::new("-80")
+  while (u.exponent >= exp) 
+    t   = t*m25
+    u,r = t.div(k,sig)
+    pi  = pi + u
+    k   = k+two
+  end
+
+  u = BigDecimal::new("1")
+  k = BigDecimal::new("1")
+  w = BigDecimal::new("1")
+  t = BigDecimal::new("956")
+  while (u.exponent >= exp )
+    t,r = t.div(m57121,sig)
+    u,r = t.div(k,sig)
+    pi  = pi + u
+    k   = k+two
+  end
+  pi
+end
+
+if $0 == __FILE__
+  if ARGV.size == 1
+    print "PI("+ARGV[0]+"):\n"
+    p big_pi(ARGV[0].to_i)
+  else
+    print "TRY: ruby pi.rb 1000 \n"
+  end
+end