How do I execute my loop at a relatively short time?

It is taking like forever (over 6 hours) to execute a loop. The size of my variables are;

Z = 2041211 element

Distance = 2021x2021 double

    for duidx = 1:Z
        Summation_Residual_Squared(duidx) = sum(Residual_Squared(Distance_Unique(duidx)==Distance));
        Semivariance(duidx) = Summation_Residual_Squared(duidx)/(2*sum(Distance(:)== Distance_Unique(duidx)));
    end

Am I working with large files such that the execution time I'm obtaining is normal or is there something i'm missing.

Thanks.

Darl.

Answer 1

[Andrei Bobrov]

Distance -> D

Distance_Unique -> DU

Residual_Squared -> RS

Summation_Residual_Squared -> SRS

Semivariance -> S

DD = D(:);
[lo,ii] = ismember(DD,DU);
SRS = accumarray(ii(lo),RS(lo));
S = SRS./accumarray(ii(lo),1);