not compatible units

[YA_10963798]

Both of the variables have the same unit, however mathcad said units are not compatible why is that?

 

[terryhendicott · Accepted solution]

Hi,

Formula does not have consistent units.

[YA_10963798]

Thank you so much for your help 

[YA_10963798]

the same problem occured again, although I followed the instructions. Can you help me with this please?

Thanks in advance

[LucMeekes]

If Mi is in MPa, then Mi^2 should be MPa^2...

So either square the MPa under Mi^2, or divide Mi by MPa before you square it:

(Mi/MPa)^2.

and

You should attach the Prime worksheet and state which version of Prime you are using.

Success!
Luc

[YA_10963798]

Oh that’s it . Thank you

one more question. How to solve the following error ?

[LucMeekes]

attach the Prime worksheet and state which version of Prime you are using

[YA_10963798]

sure 

[LucMeekes]

So, that's Prime 9.

You shouldn't evaluate a definition like you did:

(That is: do NOT put an = at the end of a definition. Yes, it works, most of the time, but it also causes trouble, more often that you wish for.)

So do:

Now exactly what are you trying to do?

you set up a summation with k running from 0 to j-1, but j is a vector because you defined it as a range and used an inline evaluation at its definition which transforms the range into a vector (undocumented behaviour that should be used with caution, if at all). Now Prime will not allow the upper limit of the summation index to be anything other than an integer scalar. So that's your problem 1.

The other problem is that your summand

(The stuff you want to sum), does not use the index k. So what is Prime supposed to do?

Success!
Luc

[LucMeekes]

If you want the elements of

 and

to be multiplied element by element and summed, you can use vectorisation, like this:

( That is 1*4 + 2*5 + 3*6 = 4+10+18 = 32)

In your case:

Success!
Luc

[YA_10963798]

This was very helpful , thanks you are the best

[YA_10963798]

I'm having the same issue again 

Why do you think so?

[Werner_E]

I would suggest that you open a new thread and attach your worksheet there.

[YA_10963798]

I did 

I attached it below as well

[Werner_E]

The sheet you attached shows a different error compared to the picture you posted above where only G(MPa is highlighted red.

I see you opened a new thread with that question and I already answered it -> https://community.ptc.com/t5/Mathcad/units-are-not-compatible/m-p/945030/highlight/true#M211406

Please also note my last answer there because I think that you don't need to divide by the units at all but you have to apply vectorization to get the desired correct results.