new pi fuction

Author: iyuangang

pi2.py

@@ -0,0 +1,44 @@
+# -*- coding: utf-8 -*-
+from __future__ import division
+import time
+#  π/4=4arctan1/5-arctan1/239
+number = int(input('please in put the No: '))
+time1=time.time()
+number1 = number+10
+
+# 算到小数点后number1位
+b = 10**number1
+
+# 求含4/5的首项
+x1 = b*4//5
+# 求含1/239的首项
+x2 = b// -239
+
+# 求第一大项
+he = x1+x2
+#设置下面循环的终点，即共计算n项
+number *= 2
+
+#循环初值=3，末值2n,步长=2
+for i in range(3,number,2):
+    # 求每个含1/5的项及符号
+    x1 //= -25
+    # 求每个含1/239的项及符号
+    x2 //= -57121
+    # 求两项之和
+    x = (x1+x2) // i
+    # 求总和
+    he += x
+
+# 求出π
+pai = he*4
+#舍掉后十位
+pai //= 10**10
+
+############ 输出圆周率π的值
+paistring=str(pai)
+result=paistring[0]+str('.')+paistring[1:len(paistring)]
+print (result)
+
+time2=time.time()
+print ("used time:"+str(time2 - time1) + 's')