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LucMeekes23-Emerald IV
23-Emerald IV
January 15, 2020
Question

Bug or feature

Ran across this:

LucMeekes_0-1579099439333.png

Has this been seen before?

And how do Mathcad 15 and Prime fare?

Hmm:

LucMeekes_0-1579099818472.png

This I can check in Prime Express:

LucMeekes_1-1579099869685.png

No error either...

 

Luc

5 replies

-MFra-21-Topaz II
21-Topaz II
January 15, 2020

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

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Werner_E
Werner_E25-Diamond I
25-Diamond I
January 15, 2020

I won't call it a bug.

Werner_E_1-1579107998177.png

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!

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LucMeekes23-Emerald IVAuthor
23-Emerald IV
January 15, 2020

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

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    Werner_E
    Werner_E25-Diamond I
    25-Diamond I
    January 15, 2020

    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 😉

    Werner_E_0-1579114448832.png

     

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