Vectorization of for loops

Question

sko 2021-2-25

0
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https://ww2.mathworks.cn/matlabcentral/answers/755819-vectorization-of-for-loops

回答： Sindhu Karri 2021-3-5

Hi Guys,

Do you have some idea how to vectorize a piece of my code related to chem eng? I have multiple for loops and although I was thought this is not good in Matlab, I dont seem to get how to vectorize them ... My Cp's and dCpdt's of chemical specie i depends on reactor space coordiante given by l, catalyst particle space coordinate given by k. dCpdt's are time derivates of Cp's definied below in the code and are related to space derivatives (that I discretized using finite difference method). nz, nr are number of reactor/particule discretization respectively, nc is number of chemical species, nreac is number of reactions. You can clearly see that depending on my system I can easily overwhelm Matlab with multiple for loops.

Thank you in advance for your suggestion.

for l=2:ent.nz+1
    for i=1:ent.nc
        rx.particle(l).Cp(i,ent.nr+1)=rx.Cg(i,l);
        
        for k=1:ent.nr
            rx.particle(l).source=0;
            
            f=@kinetics;
            reac.rate=f(rx.particle(l).Cp(:,k))
            
            for j=1:ent.nreac
                rx.particle(l).source=rx.particle(l).source+reac.nu(i,j)*reac.rate(j);
            end
            
            if k==1
                rx.particle(l).dCpdt(i,1)=(1/p.epsp)* ...
                    (3*Deff(i,l)*((rx.particle(l).Cp(i,2)-rx.particle(l).Cp(i,1))/(rx.dr^2))+rx.particle(l).source*p.rhos);
            else
                r1=(k-1)*rx.dr;
                r2=k*rx.dr;
                rx.particle(l).dCpdt(i,k)=(1/p.epsp)* ...
                    ((Deff(i,l)/(r1^2))* ...
                    ((r2^2)*(rx.particle(l).Cp(i,k+1)-rx.particle(l).Cp(i,k))/rx.dr ...
                    -(r1^2)*(rx.particle(l).Cp(i,k)-rx.particle(l).Cp(i,k-1))/rx.dr)/rx.dr+rx.particle(l).source*p.rhos);
            end
        end
    end
end