From 8f263e859e0970ce87b77addc80dec28e8fc7e82 Mon Sep 17 00:00:00 2001
From: wukong <wukong@longaeva>
Date: Tue, 5 Jun 2018 22:34:51 -0700
Subject: re-init

---
 pi.sh | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 pi.sh

(limited to 'pi.sh')

diff --git a/pi.sh b/pi.sh
new file mode 100644
index 0000000..83af08a
--- /dev/null
+++ b/pi.sh
@@ -0,0 +1,24 @@
+#!/bin/sh
+
+### pi.sh, https://en.wikipedia.org/wiki/Pi
+# In 1706 John Machin used the Gregory–Leibniz series to produce an algorithm
+# that converged much faster. Machin reached 100 digits of π with this
+# formula. Other mathematicians created variants, now known as Machin-like
+# formulae, that were used to set several successive records for calculating
+# digits of π. Machin-like formulae remained the best-known method for
+# calculating π well into the age of computers, and were used to set records
+# for 250 years, culminating in a 620-digit approximation in 1946 by Daniel
+# Ferguson–the best approximation achieved without the aid of a calculating
+# device.
+
+awk -v fig=${1} '
+    function pi() {
+        return 4*(4*atan2(1,5) - atan2(1,239))
+    }
+    BEGIN {
+        if (fig <= 0)
+            fig = 6
+        str = "%." fig "g\n"
+        printf(str, pi())
+    }
+'
-- 
cgit v1.2.3