From 6298288d58c54c6005137a28e3791153908bfc51 Mon Sep 17 00:00:00 2001
From: neingeist <neingeist@bl0rg.net>
Date: Thu, 9 May 2013 19:18:10 +0200
Subject: [PATCH] add approximation of pi

---
 Makefile         |  3 +++
 approximate-pi.c | 23 +++++++++++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 Makefile
 create mode 100644 approximate-pi.c

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..03e1c60
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,3 @@
+CFLAGS=-std=c99
+
+all: approximate-pi
diff --git a/approximate-pi.c b/approximate-pi.c
new file mode 100644
index 0000000..b25a369
--- /dev/null
+++ b/approximate-pi.c
@@ -0,0 +1,23 @@
+#include <stdio.h>
+#include <stdbool.h>
+
+double approximate_pi(unsigned int steps) {
+  double approximate_pi = 4.0;
+  bool subtract = true;
+
+  for(int i=2; i<=steps; i++) {
+    if (subtract) {
+      approximate_pi -= (4.0/(i*2-1));
+    } else {
+      approximate_pi += (4.0/(i*2-1));
+    }
+    subtract = !subtract;
+  }
+
+  return approximate_pi;
+}
+
+int main(int argc, char *argv[]) {
+  // printf("sizeof(int) = %d\n", sizeof(int));
+  printf("pi = %8.7f\n", approximate_pi(10000000));
+}