st: return null Mata

["Thomas, Anthony" <anthony_h_thomas@brown.edu>]

Hi All,

I'm sure there is an obvious answer to this question, but I can't seem
to figure it out. I have a Mata function that I want to return nothing
when some condition fails to be met (the function is ordinarily
supposed to return a string matrix). I was thinking something like:

if(something) return(NULL);

or if(something) return(0);

would work, but I get errors indicating the return type is not as
expected in either case. I'm guessing this is because NULL is really a
pointer and 0 is just being interpreted in its normal sense. How can I
get Mata to return nothing in one instance and a string matrix in
others?

Thanks,

Anthony
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