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Re: Tips for writing correct, non trivial Mathematica Libraries


>> of x + y to be  Sqrt[x y], it should be (x + y)^1 = x+ y
>
> No, it shouldn't be. There is no such thing as a mean of a number or 
an algebraic expression. What you would expect is

But something like Times[2] should be ok?  It think it's a reasonable 
matter of convention whether someone feels like a definition for 
geometric mean should expect a single vector argument, or as multiple 
arguments e.g. geom[x,y,z,=85]  but I'll admit we're quibbling at this 
point and move on.

>
> Clear[geom]
>
> geom::nonlist =
>  "The argument `1` is neither a non-empty vector nor a non-empty matrix";
>
> geom[ls_] /;If[Head[ls] === List, True, Message[geom::nonlist, x]; False] :=
> Apply[Times, ls]^(1/Length[ls])

Awesome -- this is what I was curious about!  Thanks for taking the time.


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