Implicit function solving for maximum points

Hi everyone

I am trying to solve for the maximum Vmpp_(:,:,K) and Impp_(:,:,K) points. The program runs but the results I get do not make sense! Please let me know if you have any comments, my code is:

    Vmpp_(:,:,K) = Voc_GT(:,:,K)./Voc_ref(K).*Vmp_ref(K);
    Impp_(:,:,K) = Isc_GT(:,:,K)./Isc_ref(K).*Imp_ref(K);
    w  = 0.04; % for SUR

    for iteration = 1:10000

        Vmpp_(:,:,K) = (1-w).*Vmpp_(:,:,K)+w.*(Voc_GT(:,:,K)-Impp_(:,:,K).*Rs(K)+ns(K).*Vt(:,:,K)...
            .*log(((Isc_GT(:,:,K)-Impp_(:,:,K)).*(Rs(K)+Rsh(:,:,K))-Vmpp_(:,:,K))./(Isc_GT(:,:,K)...
            .*(Rs(K)+Rsh(:,:,K))-Voc_GT(:,:,K))));

        Impp_(:,:,K) = (1-w).*Impp_(:,:,K)+w.*(Vmpp_(:,:,K).*(1./Rsh(:,:,K)+(Isc_GT(:,:,K)...
            .*Rsh(:,:,K)-Voc_GT(:,:,K)+Isc_GT(:,:,K).*Rs(K)).*exp((Vmpp_(:,:,K)+Impp_(:,:,K)...
            .*Rs(K)-Voc_GT(:,:,K))/ns(K)./Vt(:,:,K))./ns(K)./Vt(:,:,K)./Rsh(:,:,K))./(1+Rs(K)...
            ./Rsh(:,:,K)+Rs(K).*(Isc_GT(:,:,K).*Rsh(:,:,K)-Voc_GT(:,:,K)+Isc_GT(:,:,K).*Rs(K))...
            .*exp((Vmpp_(:,:,K)+Impp_(:,:,K).*Rs(K)-Voc_GT(:,:,K))./ns(K)./Vt(:,:,K))./ns(K)./Vt(:,:,K)./Rsh(:,:,K)));