Sum in Mathcad Prime

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@LucMeekes wrote:

Stuart,

 

Not odd. The 'magic' is in the fact that Valery put an evaluation (=) after the range definition of i. That changes the range to a vector. This is a special feature of Prime.

With that evaluation your sheet shows:

The summation with a single i at its bottom, requires i to be a range; vector is not allowed.

 

Success!
Luc

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Ah, of course.  Thanks, Luc.  I definitely need those new glasses! 

I did know about this "feature", but I tend to avoid putting evaluation operators at the end of definitions, precisely because of such side effects.   I don't think that it's entirely clear from the rhs of the evaluation what the definition will actually assign to the variable.

IMO, for this purpose, they'd have been better off implementing a vec function that converts any argument to a vector. 

I believe that I've suggested in the past that Mathcad ought to auto-iterate over vectors (or arrays, in general) in such cases.   I vaguely recall having a discussion about this some time ago and there being some objections - but I can't remember what they were.  I'll have to have a think about it.  I vaguely recall Tom Gutman and jMG commenting ...

However, the feature request for an automatic vector product still stands.  🙂

Cheers,

Stuart

(I also wonder if min and max ought to return the first and last elements of a range ...I can think of a few uses for this capability?)