[Scilab-users] Slight inconsistency and suggested mprovement in max / min / mean etc.

[Federico Miyara]

Dear all,

I've seen that functions like max, min, sum, prod, cumsum, cumprod, 
mean, median, stdev are similar in that they act on several data 
returning a scalar result. If "r" or "c" are includedas an additional 
argument, they operate along rows or columns.

Except for max and min, they all accept 1 and 2 instead of "r" and "c". 
By the way, in several help pages this possibility is presented as a 
side note.

I understand this slight difference is to allow the comparison of a 
whole array with a scalar, so that max(x,1), for instance, is an array 
whose components are the maximum between the original components and 1.

This prevents using the general syntax max(x,1) which would be more 
consistent, allowing its genaralization as max(x,n) where n is the 
dimension along which the requested operation would be performed.

Currently n may be only 1 and 2, but there is no reason why it couldn't 
be any other dimension. For instance, calling the third 
dimension"layer", max(x,3) would mean getting the maximum of a row and 
column along different layers. This could be used, for instance, to get 
the most brilliant version of a pixel along successive frames in a movie.

To keep the comparison-with-a-scalar feature, it would be enough to 
place the scalar first: max(1,x). The only caution needed in this kind 
of comparisons is that if there is at least one non-scalar array in the 
comparison list, the last item should be non-scalar.

Regards,

Federico Miyara

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