topic Re: Bug or feature in Mathcad

Bug or feature

LucMeekes — Wed, 15 Jan 2020 14:51:39 GMT

Ran across this:

Has this been seen before?

And how do Mathcad 15 and Prime fare?

Hmm:

This I can check in Prime Express:

No error either...

Luc

Re: Bug or feature

-MFra- — Wed, 15 Jan 2020 16:32:48 GMT

evidently a matrix cannot be assigned to a vector. In fact, only the first column is transferred.

Re: Bug or feature

Werner_E — Wed, 15 Jan 2020 17:24:16 GMT

I won't call it a bug.

Trying to assign a multiple column matrix to a column vector may result in an error. Mathcad decides against that and only considers the first column of the matrix and only the necessary number of rows.
Its a matter of taste if you find that this an irritation behaviour or consider it a feature.

BTW, which values did you expect A and B to hold after the assignment? Row vectors?

Keep in mind that a matrix is NOT a vector of row vectors!

Re: Bug or feature

LucMeekes — Wed, 15 Jan 2020 18:07:14 GMT

In fact, I was expecting an error message. Why do I get an error message on trying to transpose a scalar, and not on this? This can make expressions appear to work, but in fact work in mysterious ways. So I think an error message is due here.

Luc

Re: Bug or feature

Werner_E — Wed, 15 Jan 2020 19:03:51 GMT

I overlooked that you had already written that you expected an error in your initial post.

Nevertheless, as already written, I consider it a matter of personal taste if you think that it must yield an error.

Trying to transpose a scalar sure is not possible as a scalar is not a 1x1 matrix, but assigning a matrix to another matrix, even if the source is larger, may make sense. Its not necessarily wrong for a software if it simply ignores the superfluous values.

You may see it as a way to get the upper left submatrix of a larger matrix 😉

Re: Bug or feature

ValeryOchkov — Thu, 16 Jan 2020 08:34:30 GMT

Pardon