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I am using GRQUICK package for calculation of Ricci tensors. I am using a non diagonal metric with coefficients being functions of two co-ordinates. I want to know if the highlighted expression denotes partial derivates or something entirely different.

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    $\begingroup$ It represents derivative of v[r,theta] w.r.t theta once. $\endgroup$
    – zhk
    Feb 22, 2017 at 7:14
  • $\begingroup$ You can caopy and paste and use FullForm to check what is there. $\endgroup$
    – Kuba
    Feb 22, 2017 at 7:19
  • $\begingroup$ Thanks !! v[r,theta] w.r.t theta once.. Could you tell me the logic to understand that ? r corresponds to 1 while theta corresponds to 2. For example what would you make of v(2,0) term similarly ? $\endgroup$
    – Astronomer
    Feb 22, 2017 at 7:20

1 Answer 1

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Well, you need to see help on D.

D[v[r, t], t]  (*it gives partial derivative of v w.r.t t once*)

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Here the superscript (0,1) means that v[r,t] is partially differentiated once w.r.t t thats why you have 1 on right side because in the argument [r, t], t is on the right side.

Now, if you want to differentiate v w.r.t r, then

D[v[r, t], r]  (*it gives partial derivative of v w.r.t r once*)

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D[D[v[r, t], r], r]  (*it gives partial derivative of v w.r.t r twice*)

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Does this make any sense?

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  • $\begingroup$ Yes ! Many thanks. Now its crystal clear :-) $\endgroup$
    – Astronomer
    Feb 22, 2017 at 7:34
  • $\begingroup$ @AravindRavi Happy to help. $\endgroup$
    – zhk
    Feb 22, 2017 at 7:36

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