add hg and python

1 files changed, 34 insertions, 0 deletions

diff --git a/sys/src/cmd/python/Demo/scripts/pi.py b/sys/src/cmd/python/Demo/scripts/pi.py
new file mode 100755
index 000000000..9b242451a
--- /dev/null
+++ b/sys/src/cmd/python/Demo/scripts/pi.py
@@ -0,0 +1,34 @@
+#! /usr/bin/env python
+
+# Print digits of pi forever.
+#
+# The algorithm, using Python's 'long' integers ("bignums"), works
+# with continued fractions, and was conceived by Lambert Meertens.
+#
+# See also the ABC Programmer's Handbook, by Geurts, Meertens & Pemberton,
+# published by Prentice-Hall (UK) Ltd., 1990.
+
+import sys
+
+def main():
+    k, a, b, a1, b1 = 2L, 4L, 1L, 12L, 4L
+    while 1:
+        # Next approximation
+        p, q, k = k*k, 2L*k+1L, k+1L
+        a, b, a1, b1 = a1, b1, p*a+q*a1, p*b+q*b1
+        # Print common digits
+        d, d1 = a/b, a1/b1
+        while d == d1:
+            output(d)
+            a, a1 = 10L*(a%b), 10L*(a1%b1)
+            d, d1 = a/b, a1/b1
+
+def output(d):
+    # Use write() to avoid spaces between the digits
+    # Use str() to avoid the 'L'
+    sys.stdout.write(str(d))
+    # Flush so the output is seen immediately
+    sys.stdout.flush()
+
+if __name__ == "__main__":
+    main()