how can i sum over to variable in matlab?
28 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
Hi, i have a function as below in a for loop:
for i=1:20
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/159970/image.gif)
end;
i'm trying to sum over variables N,N', as simple as it looks, it confused me? can any one help?
thanyou so much in advance
4 commentaires
Guillaume
le 19 Jan 2017
And can these function operate on matrices, or do they only accept scalars?
Réponses (2)
Jorge Mario Guerra González
le 19 Jan 2017
Modifié(e) : Jorge Mario Guerra González
le 19 Jan 2017
you mean something like this....
I'm supposing F,K,G are random arrays,
are N and N' independent values??? because the notation N, N' is a little tricky for me.
F=rand(20,20);
G=rand(1,20);
K=rand(1,20);
suma=0;
for i=1:20
for j=1:20
suma=suma+F(i,j)*G(i)*K(j);
end
end
disp(suma);
%where i and j are your N and N'
5 commentaires
Jorge Mario Guerra González
le 19 Jan 2017
@Joseph you should've specified that N=N'-1 in the question. So, since N=N'-1 the range of N is 0:19?. why does the equation you posted say N=1:20.
Guillaume
le 19 Jan 2017
Modifié(e) : Guillaume
le 19 Jan 2017
Without any a priori knowledge of F, G, K, this is guaranteed to work:
[NN1, NN2] = ndgrid(0:19, 1:20); %all combinations of N and N'
FN = arrayfun(@F, NN1, NN2);
GN = arrayfun(@G, NN1);
KN = arrayfun(@K, NN2);
result = sum(sum(FN .* GN .* KN)); %or sum(FN(:) .* GN(:) .* KN(:)) which is probably faster but more cryptic.
If the F, G, K functions support implicit expansion or can work directly with vectors and matrices then the arrayfun lines would not even be needed.
0 commentaires
Voir également
Catégories
En savoir plus sur Quantum Mechanics dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!