diff --git a/pibench.rb b/pibench.rb
new file mode 100644
index 0000000..e868261
--- /dev/null
+++ b/pibench.rb
@@ -0,0 +1,33 @@
+#!/usr/bin/env ruby
+# From: http://imetrics.co.jp/math2/Pi-with-Ruby.pdf
+require "bigdecimal"
+require "benchmark"
+result = Benchmark.realtime do
+  prec = 10
+  conv = 6
+  a = BigDecimal("1")
+  b = BigDecimal("1") / BigDecimal("2").sqrt(prec)
+  t = BigDecimal("1") / 4
+  p = BigDecimal("1")
+  for n in 1..conv do
+    an = (a + b) / 2
+    b = (a * b).sqrt(prec)
+    t -= p * (an - a) * (an - a)
+    p *= 2
+    a = an
+  end
+  puts (a + b) * (a + b) / (4 * t)
+end
+puts "Time: #{result}s"
+
+include Math
+a=1.0; b=1/sqrt(2); t=1.0/4; p=1.0
+6.times do
+  an = (a+b)/2
+  b  = sqrt(a*b)
+  t -= p*(an-a)*(an-a)
+  p *= 2
+  a  = an
+  p a
+end
+  puts (a + b) * (a + b) / (4.0 * t)
diff --git a/taylor.rb b/taylor.rb
new file mode 100755
index 0000000..dbc8f3c
--- /dev/null
+++ b/taylor.rb
@@ -0,0 +1,29 @@
+#!/usr/bin/env ruby
+require 'bigdecimal'
+
+goal = (ARGV[0]||9999).to_i
+if true
+pi4 = 0.0
+(0..goal).each do |x|
+  pi4 += (-1)**x * 1.0/(2*x+1)
+end
+printf("pi=%.20f\n", 4*pi4)
+printf("ep=%.20f\n", Math::PI-4*pi4)
+end
+
+pi4 = 0.0
+goal.step(0, -1) do |x|
+  pi4 += (-1)**x * 1.0/(2*x+1)
+end
+printf("pi=%.20f\n", 4*pi4)
+printf("ep=%.20f\n", Math::PI-4*pi4)
+
+pi4 = 0
+bai = 10**20
+
+(0..goal).each do |i|
+  pi4 += (-1)**i * bai/(2*i+1)
+  #printf("%d\r", i)
+end
+printf("pi=%.20f\n", 4.0*pi4/bai)
+printf("ep=%.20f\n", Math::PI-4.0*pi4/bai)