From 0d7e9e593615704ab6265941e8c61bc1f8f4cdd9 Mon Sep 17 00:00:00 2001
From: "Jeffrey A. Ryan" <jeff.a.ryan@gmail.com>
Date: Thu, 11 Mar 2010 21:45:23 +0000
Subject: [PATCH] added check for missing n when ratio is specified to EMA. If
 missing, converts n to approx. "correct" value given ratio

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/ttr/pkg@98 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
---
 R/MovingAverages.R | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/R/MovingAverages.R b/R/MovingAverages.R
index 9e0c909..9e5276f 100755
--- a/R/MovingAverages.R
+++ b/R/MovingAverages.R
@@ -51,6 +51,11 @@ function (x, n=10, wilder=FALSE, ratio=NULL) {
   # Check for non-leading NAs
   # Leading NAs are handled in the C code
   x.na <- xts:::naCheck(x, n)
+  
+  # If ratio is specified, and n is not, set n to approx 'correct'
+  # value backed out from ratio
+  if(missing(n) && !missing(ratio))
+    n <- trunc(2/ratio - 1)
 
   # Determine decay ratio
   if(is.null(ratio)) {