add case Attributes provided but not shot

matlab/CHDF/cdf2mat.m

@@ -136,7 +136,15 @@ end
 if ~isempty(allinfo.Attributes)
   top_attr_names = {allinfo.Attributes(:).Name};
   ij = strmatch('shot',top_attr_names,'exact');
-  cdf2mat_out.shot = allinfo.Attributes(ij).Value;
+  if ~isempty(ij)
+    cdf2mat_out.shot = allinfo.Attributes(ij).Value;
+  else
+    if nargin>1 && isnumeric(varargin{1})
+      cdf2mat_out.shot = varargin{1};
+    else
+      cdf2mat_out.shot = NaN;
+    end
+  end
 else
   if nargin>1 && isnumeric(varargin{1})
     cdf2mat_out.shot = varargin{1};