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Mathcad derivative

prajendran
11-Garnet

Mathcad derivative

I'm trying to take the derivative of a function with respect to t but it shows as 0 when it is not. could you please help?

Thanks

Prashanth Rajendran

prajendran_0-1619467299537.png

 

5 REPLIES 5
LucMeekes
23-Emerald III
(To:prajendran)

You've been hit by Prime's infamous autolabelling feature.

The t in the d/dt is labelled an automatic (variable):

LucMeekes_0-1619600418348.png

instead of a real variable:

LucMeekes_1-1619600541232.png

So change its label to variable and all should be as expected.

 

Success!
Luc

ttokoro
20-Turquoise
(To:prajendran)

Prime7 shows no error.

image.png

I can verify the error in Prime 4 and Prime 5 by opening the original sheet and recalculating it (after deleting all the irrelevant and time consuming regions).
As shown by Luc the workaround is manually labelling the t in the derivative operator as "Variable".

 

In Prime 6 this bug seems to be fixed - I verified it with both symbolic engines available in P6 (muPad and FreeCAS). So no surprise that its still fixed in P7 😉

 

 

I'm using 3.1 though


@prajendran wrote:

I'm using 3.1 though


As already written - this is a bug and this bug was only fixed in Prime 6.
So, unless you intend to update your version (which IMHO would not be worth the money), you will have to resort to some kind of workaround.

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