From 0c533a1250ec1a1c6966db7854beb2b8fe5ea78e Mon Sep 17 00:00:00 2001
From: Eugeniy Mikhailov <evgmik@gmail.com>
Date: Tue, 17 Sep 2013 16:01:08 -0400
Subject: cavity stability finction

---
 isCavityStable.m | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 isCavityStable.m

diff --git a/isCavityStable.m b/isCavityStable.m
new file mode 100644
index 0000000..86dbd99
--- /dev/null
+++ b/isCavityStable.m
@@ -0,0 +1,19 @@
+function ret=isCavityStable (abcd_cavity) 
+    % finds if a cavity is stable baced on its abcd matrix
+    % see eq.4 for stability condition
+    % doi:10.1088/1464-4258/7/1/002
+    % http://dx.doi.org/10.1088/1464-4258/7/1/002
+
+    A=abcd_cavity(1,1);
+    B=abcd_cavity(1,2);
+    C=abcd_cavity(2,1);
+    D=abcd_cavity(2,2);
+
+    u= (A+D+2)/4
+    if ( (0 < u) && (u < 1) )
+        ret = true;
+    else
+        ret = false;
+    end
+
+end
-- 
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