Derivative over double summation?
10 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Please, can someone help me find the derivatives in this attachment? You can solve it in the attached excel document or solve it in word document and post the snap shot of the solution. Thank you so much.
![derivatives over double summation.JPG](https://www.mathworks.com/matlabcentral/answers/uploaded_files/200641/derivatives%20over%20double%20summation.jpeg)
4 Kommentare
David Goodmanson
am 13 Jan. 2019
Hi Samuel,
so by dP/dm do you mean a matrix whose ij component is dP/dm_ij?
Also the summand in each of the double sums defining P is identical, so the two double sums are almost identical, differing only in slight chages in the upper limits. Is this what is intended?
Antworten (1)
Walter Roberson
am 13 Jan. 2019
The derivative of absolute value is not well defined.
8 Kommentare
Walter Roberson
am 14 Jan. 2019
The solution is as I gave before with the difference of sign() , but remember you need to be careful on the boundary condition .
The derivative is 0 except for at most two terms because the m variable are independent except the two cases of identical subscripts. So you can break it down to three cases, one for each of the two boundary conditions and one for the centre. You can then vectorize for the centre and vectorize for each of the two boundary conditions . or perhaps it works out to be four boundary conditions . Small number of them anyhow .
Siehe auch
Kategorien
Mehr zu Startup and Shutdown finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!