From: Ramakrishnan Muthukrishnan <vu3rdd@gmail.com>
Date: Sat, 6 Aug 2011 19:21:16 +0000 (+0530)
Subject: added integral to streams library
X-Git-Url: https://git.rkrishnan.org/frontends/listings/pb3calculator.py?a=commitdiff_plain;h=7bae9f6c273d2ecad8bee324d57802f3ecad6fe3;p=sicp.git

added integral to streams library
---

diff --git a/src/sicp/streams.rkt b/src/sicp/streams.rkt
index b68afe1..e4252cd 100644
--- a/src/sicp/streams.rkt
+++ b/src/sicp/streams.rkt
@@ -120,4 +120,9 @@
                 (stream-cdr t))
     (pairs (stream-cdr s) (stream-cdr t)))))
 
-   
+(define (integral integrand initial-value dt)
+  (define int
+    (cons-stream initial-value
+                 (add-streams (scale-stream integrand dt)
+                              int)))
+  int)