topic Re: matrix gives [1x1] as result, why? in Mathcad

matrix gives [1x1] as result, why?

Seb — Sat, 26 Feb 2022 20:27:25 GMT

Dear all,

can anybody please tell me why I get [1x1] as a result for Acyl on page 4 of the attached document?

I don´t know what I am doing wrong but with this results I can not use it in the further calculations.

Thank you in advance.

Regards

Seb

Re: matrix gives [1x1] as result, why?

Werner_E — Sat, 26 Feb 2022 21:17:34 GMT

[1x1] means that you have created a matrix with one element in it. So the result is hidden in a nested matrix (you could expand via the options it to see the number calculated).

I have not yet looked at your sheet, but the reason might be that you manually typed a square bracket instead of a pair of parentheses.

Typing a square bracket creates a matrix!

EDIT: A look at your file has now confirmed my assumption. Replace the square brackets and everything works as expected.

Re: matrix gives [1x1] as result, why?

StuartBruff — Sat, 26 Feb 2022 21:15:04 GMT

@Werner_E wrote:

[1x1] means that you have created a matrix with one element in it and this element is a 1x1 matrix itself. So the result is hidden in a nested matrix (you could expand via the options it to see the number calculated).

I have not yet looked at your sheet, but the reason might be that you manually typed a square bracket instead of a pair of parentheses.

Typing a square bracket creates a matrix!

Indeed, that's exactly what the OP has done. The Qcyl_12 and Qcyl_13 expressions are surrounded by square brackets instead of parentheses. Replacing them fixes the problem.

Stuart

Re: matrix gives [1x1] as result, why?

ttokoro — Sun, 27 Feb 2022 07:26:52 GMT

Re: matrix gives [1x1] as result, why?

Werner_E — Sun, 27 Feb 2022 08:45:36 GMT

Apart from the confusion with [ ] vs ( ) I wonder what the reason for the sums in you matrix should be. After all no summand is really dependent on t or n and the matrix could be calculated much easier like shown in the following pic:

Re: matrix gives [1x1] as result, why?

Seb — Sun, 27 Feb 2022 11:59:46 GMT

@Werner_E:

Thank you for your advice

I got the equations from Schürmann Helmut. Konstruieren mit Faser-Kunststoff-Verbunde. s.1.: Springer, 2007. ISBN 978-3-540-72189-5, Chapter 10

However, it is possible that I made a mistake in the definition of n. I would be very grateful for any further help.

Regards

Seb

Re: matrix gives [1x1] as result, why?

Werner_E — Sun, 27 Feb 2022 15:09:45 GMT

Technically, I don't have the slightest knowledge of what you're doing.

But the sums in your matrix would only make sense if the summands that are added up there were dependent on the running index t. And thats not the case in your calculation and so you add up the same product (a Q.cylxx times h.t.) n times. So you could just omit the sum and simply multiply the addend by n. And since n*h.t = h, you can use that too.

If the thickness of each layer is not the same (then h.t would depend on t) the sums would make sense and so maybe your calculation is correct anyway and just can be simplified the way I had shown because you just deal with layers of equal thickness. But I don't know that for sure - I just noticed that the sums would not be necessary mathematically and could be replaced by a simpler multiplication..

So maybe someone who is technically familiar with the matter can say something more about it.