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scottytwee4-Participant
4-Participant
February 19, 2025
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Another 'This value must be a scalar or matrix' Mathcad Express Prime 10.0.0 problem

  • February 19, 2025
  • 1 reply
  • 515 views

Hello,

 

Sorry I know this issue has been raised before and I have searched but the proposed solution to that specific problem was beyond my knowledge of mathematical languages. 

 

I have defined a range (via step range) to give me a list of values to input into an equation to allow me to graph the result. This worked fine in previous versions but since upgrading to 10 it has become broken. I understand that its something to do with how Mathcad Prime defines vectors now or something but I can't seem to get this to now work. Any pointers would be greatly appreciated. I have attached a few screenshots of the problemSince the update I get these errorsSince the update I get these errorsBefore the update...working fine and allowing me to plot on a graphBefore the update...working fine and allowing me to plot on a graph

Best answer by Werner_E

1) The error in the definition of Wall stems from the fact that you changed the unit in the result to mm. If you let Prime chose the unit (usually meter) the error disappears.

Unit manually changed to mm

Werner_E_0-1739977017657.png

Unit at the end completely deleted and chosen automatically:

Werner_E_1-1739977077875.png

This behaviour is the very same in Prime 9 (actually the screen shots are from P9) and so your last screenshot sure stems from a version prior to Prime 9, right? I just tested with Prime 6 and here changing the display unit works OK and does not throw an error.

 

2) This is the main problem. Up to Prime 9 what you did (defining a range and evaluating it in the same region) converted the range into a vector. Thats the reason your last expression works. This was broken by PTC on purpose with version 10. So even when you use inline evaluation, the variable Wall remains being a range and not a vector.

So you have to make "Wall"  a vector using a different method because unfortunately PTC did not provide any means to do so (they promised to deliver in next version).

One way is to define Wall as a vector right ahead.:

Werner_E_2-1739977450157.png

or a little bit more sophisticated using start, end value and step width to determine the last index (56)

Werner_E_3-1739977595524.png

 

Another way is to define Wall as a range as you did (without using the inline evaluation) and then use a utility function which turns a range into a vector. Some of that kind of functions were posted here in the forum, some more, some less sophisticated.

Here is a simple one:

Werner_E_5-1739978106198.png

 

For future question: Please always attach your worksheet!

 

Attached sheet is in Prime 9 format.

 

 

 

 

 

 

 

 

1 reply

W
Werner_E25-Diamond IAnswer
25-Diamond I
February 19, 2025

1) The error in the definition of Wall stems from the fact that you changed the unit in the result to mm. If you let Prime chose the unit (usually meter) the error disappears.

Unit manually changed to mm

Werner_E_0-1739977017657.png

Unit at the end completely deleted and chosen automatically:

Werner_E_1-1739977077875.png

This behaviour is the very same in Prime 9 (actually the screen shots are from P9) and so your last screenshot sure stems from a version prior to Prime 9, right? I just tested with Prime 6 and here changing the display unit works OK and does not throw an error.

 

2) This is the main problem. Up to Prime 9 what you did (defining a range and evaluating it in the same region) converted the range into a vector. Thats the reason your last expression works. This was broken by PTC on purpose with version 10. So even when you use inline evaluation, the variable Wall remains being a range and not a vector.

So you have to make "Wall"  a vector using a different method because unfortunately PTC did not provide any means to do so (they promised to deliver in next version).

One way is to define Wall as a vector right ahead.:

Werner_E_2-1739977450157.png

or a little bit more sophisticated using start, end value and step width to determine the last index (56)

Werner_E_3-1739977595524.png

 

Another way is to define Wall as a range as you did (without using the inline evaluation) and then use a utility function which turns a range into a vector. Some of that kind of functions were posted here in the forum, some more, some less sophisticated.

Here is a simple one:

Werner_E_5-1739978106198.png

 

For future question: Please always attach your worksheet!

 

Attached sheet is in Prime 9 format.

 

 

 

 

 

 

 

 

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