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authorDavid Thompson <dave@izanagi>2013-06-23 10:56:35 -0400
committerDavid Thompson <dave@izanagi>2013-06-23 10:56:35 -0400
commit4e6d8acd9cab2841178080db8dfd921f0434a8e7 (patch)
tree55beca6ca6ba5819651685aa4938e57b9ebf196b
parentbff4c4aa7e4674d87e8ded3cdde4ee6a6cc8a8c2 (diff)
Add vector math module.
-rw-r--r--2d/vector.scm66
1 files changed, 66 insertions, 0 deletions
diff --git a/2d/vector.scm b/2d/vector.scm
new file mode 100644
index 0000000..9dc1e1b
--- /dev/null
+++ b/2d/vector.scm
@@ -0,0 +1,66 @@
+;;; guile-2d
+;;; Copyright (C) 2013 David Thompson <dthompson2@worcester.edu>
+;;;
+;;; Guile-2d is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU Lesser General Public License as
+;;; published by the Free Software Foundation, either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; Guile-2d is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+;;; Lesser General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU Lesser General Public
+;;; License along with this program. If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+;;
+;; Vector math operations.
+;;
+;;; Code:
+
+(define-module (2d vector)
+ #:use-module (rnrs base)
+ #:export (v+
+ v*
+ scale
+ mag
+ normalize
+ vector-reduce))
+
+(define (v+ . vectors)
+ "Adds vectors."
+ (apply vector-map + vectors))
+
+(define (v* . vectors)
+ "Multiplies vectors."
+ (apply vector-map * vectors))
+
+(define (scale vector scalar)
+ "Multiplies a vector by a scalar."
+ (vector-map (lambda (e) (* scalar e)) vector))
+
+(define (mag vector)
+ "Returns the magnitude of a vector."
+ (sqrt (vector-reduce + 0 (vector-map (lambda (e) (* e e)) vector))))
+
+(define (normalize vector)
+ "Normalizes a vector."
+ (let ((m (magnitude vector)))
+ (vector-map (lambda (e) (/ e m)) vector)))
+
+(define (vector-reduce proc default vector)
+ "Performs a reduce operation on a vector."
+ (cond ((= (vector-length vector) 0)
+ default)
+ ((= (vector-length vector) 1)
+ (vector-ref vector 0))
+ (else
+ (let loop ((i 2)
+ (prev (proc (vector-ref vector 0)
+ (vector-ref vector 1))))
+ (if (= (vector-length vector) i)
+ prev
+ (loop (1+ i) (proc prev (vector-ref vector i))))))))