diff --git a/matlab/set_default_option.m b/matlab/set_default_option.m
index 3c8303f76bacde13ef4fd6c02a060b20d03b801a..760d74fa86f8ed428a064fc57998033a43e064c8 100644
--- a/matlab/set_default_option.m
+++ b/matlab/set_default_option.m
@@ -33,6 +33,17 @@ function options=set_default_option(options,field,default)
 
 if ~isfield(options,field)
     options.(field) = default;
+    return
+end
+
+if isempty(options.(field))
+    options.(field) = default;
+    return
+end
+
+if isnan(options.(field))
+    options.(field) = default;
+    return
 end
 
 % 06/07/03 MJ added ; to eval expression
\ No newline at end of file