Require to differentiate wrt Fourier coefficient Mathcad Prime 8

[FK_10732959]

Hi guys, I am doing my master's dissertation and i have come across a problem. I have in my sheet Fourier series which is used to show displacement field in this research i am doing. The problem is that by the end of my calculations i have to differentiate a few equations with these Fourier coefficients. I am but unable to do this as in the differentiation operator i am unable to use anything other than variables in the denominator, i am unable to have the index operator in the denominator of the differential equation. I have just started working with Mathcad a month ago. I  have attached two pics to show what i am trying to get at. Any help would be really appreciated. Thank you. 

[Werner_E · Accepted solution]

Its not really clear to me what you are actually trying to do and from the pics we don't see how you defined your variables and/or functions (I don't see any function in your pics!).

But its true that its a bad limitation of Prime that it can't handle vector functions pretty good and won't allow an indexed variable as variable of derivation.

Not sure but maybe the Nabla operator can be handy?

[FK_10732959]

Hey, thanks for replying. Yea i couldn't explain the problem with the pics because the equations were too big. But you seem to have understood the problem anyways. I'll tr with the nabla operator now. i think it would work for me.

Thanks again for your help.

[FK_10732959]

hey, btw can you tell me where can i find nabla operator here? I am trying to find it but am unable to do so

[LucMeekes]

Search the online help for it...?

Or was it introduced in Prime 9 ?

Success!

Luc

[Werner_E]

Oops, sorry! I'm afraid the Nabla (gradient) operator was only introduced with version 9 and you are using Prime 8 😞

In fact the operator was re-introduced, because in real Mathcad (version 15 and below) it has "always" existed. But Prime still has a long way to go before it is somewhat on par with good old Mathcad, if ever 😞

Here is a somewhat awkward workaround, maybe it can be of help to you:

You may use the substitute modifier to get a result in the vector elements and can create a function for the partial derivative

[FK_10732959]

Ah, thanks, i am doing that right now and also i tried using the nabla operator and i keep getting insufficient memory errors. So now i am induvidually differentiating them by further breaking down the equations. Is there any method to get around the insufficient memory error, other than breaking down the equations? because i have 16 gigs of ram in my pc but it is not even utilizing the whole memory.

[Werner_E]

Can't comment on the memory error. On contrary to old Mathcad (15 and below), Prime should be able to utilize all of the RAM your machine provides if it needs it and the mem is not used by other software.