X-Git-Url: http://git.kpe.io/?p=kmrcl.git;a=blobdiff_plain;f=math.lisp;h=b3df9d6a045e0fb66938e21f0bdf7d7acb3a364e;hp=fcbab3c4baa2e922b0eba049af0bd04079a19739;hb=b43594669e466089305948a40cfacd1b63b0767a;hpb=ad1c18be22d33d7dbda5344c801ee62c3e069072

diff --git a/math.lisp b/math.lisp
index fcbab3c..b3df9d6 100644
--- a/math.lisp
+++ b/math.lisp
@@ -96,3 +96,15 @@
 		       (double-float double-float-epsilon)
 		       (long-float long-float-epsilon))
 		     (- exponent 1.0-exponent))))))
+
+(defun sinc (x)
+  (if (zerop x)
+      1d0
+    (let ((x (coerce x 'double-float)))
+      (/ (sin x) x))))
+
+
+(defun number-within-percentage (a b percent)
+  "Determines if two numbers are equal within a percentage difference."
+  (let ((abs-diff (* 0.01 percent 0.5 (+ (abs a) (abs b)))))
+    (< (abs (- a b)) abs-diff)))