From 0525bcc690cafa10a30e3cf2490e52695a8f7309 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Mon, 15 Jul 2013 22:36:27 -0400
Subject: Add vector-from-polar procedure.

---
 2d/vector.scm | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to '2d')

diff --git a/2d/vector.scm b/2d/vector.scm
index 7dcbcb2..bd14dd5 100644
--- a/2d/vector.scm
+++ b/2d/vector.scm
@@ -31,7 +31,8 @@
             scale
             mag
             normalize
-            vector-reduce))
+            vector-reduce
+            vector-from-polar))
 
 (define (vx vector)
   "Returns the first element of a vector."
@@ -79,3 +80,7 @@
            (if (= (vector-length vector) i)
                prev
                (loop (1+ i) (proc prev (vector-ref vector i))))))))
+
+(define (vector-from-polar r theta)
+  (vector (* r (cos theta))
+          (* r (sin theta))))
-- 
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