I am new to Mathcad and am getting the error "unable to form derivative matrix" when using OdeSolve. I think I may not be able to use OdeSolve inline like I am doing, so I tried putting it outside of the solve block as well. Can anyone confirm this? And what should I do instead? I appreciate your help. I am re-posting this because I have changed the code since then thanks to help, but am still getting the same issue. The file is attached, and the screenshots are displayed below.
I fixed part of the issue by using the differential operators in the drop down menu instead of just typing d/dt. However, now i get "units are not compatible". Does anyone see why?
> Does anyone see why?
I already told your here: Mathcad Prime 2.0 Coding issue
Two of your summands have a wrong unit / dimension. Somehow you have to check again your equations. Those summands must be divided by liter ot the like.
I just see that in the other thread you wrote that you fixed the problem and found the solution you were looking for.
Hi tj lafata,
you have to do even this small correction:
You have to use as a derivative the operator defined by mathcad. You can't write d/dt Lb(t)...
Assuming that the last term in second member of the second and third equation, is not multiplied by Vl, you have:
or dividing, for example by Vb the last term in second member of the second and third equation, you have:
According to his post yesterday Apr 5, 2017 9:07 PM he found out about the derivative operator himself and according to gis post in the other thread I referred to he already fixed the unit problem.
You should close this threads to make clear that the problem is already solved.
Thanks Werner, I had not noticed the communication of tj lafata, preferring. above all, to find a solution to the problem.
We look forward to the closing of this discussion by tj Lafata.