Using for loop within a for loop in MATLAB

I need to apply For loop within a loop. As of generally, we apply a for loop(Say j as i used) and for that value another loop( say i here) runs all the statements but here I need to reuse that first loop( j ) again within the statements. If I could get some idea, how to use it repeatedly.

%%Calculate molar volume of solvent mixture
%xm=composition of species in solution
%Vc=critical volume of species
%vm=molar volume of species
%Tr=reduced temperature of species
%T=temperature of solution mixture
%V= molar volume of micture
Vc= [121.90 55.9 155];
Zc= [0.287 0.229 0.265];
Tc= [423.85 647.1 819.15];
xm= [0.1 0.2 0.2];
T=[394.15 399.15 404.15];
V=[0 0 0];
N=length(T);
vm=[0 0 0];
v=[0 0 0];
Tr=[0 0 0];
for j=1:N
    if (T(j)<=423.85)
    for i=1:1
    Tr(i)=T(j)/Tc(i);
    vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
    v(i)=xm(i)*vm(i);
    end
    elseif (423.85<T(j))&&(T(j)<=647.1)
        for i=1
                T= 423.85; %Constant critical temperature of HI
                 Tr(i)=T/Tc(i);
                 vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
                  v(i)=xm(i)*vm(i); 
                for i=2:3
                    T=T(j)
                 Tr(i)=T(j)/Tc(i);
                 vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
                  v(i)=xm(i)*vm(i);
                end
        end
    elseif (647.1<T(j))&&(T(j)<=819.15)
        for i=1
            T=423.85;
                 Tr(i)=T/Tc(i);
                 vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
                  v(i)=xm(i)*vm(i);
               for i=2
                      T=647.1; % critical temperature of H2O
                      Tr(i)=T/Tc(i);
                       vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
                       v(i)=xm(i)*vm(i); 
                 for i=3
                   T=T(j);
                        Tr(i)=T(j)/Tc(i);
                        vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
                        v(i)=xm(i)*vm(i);
                 end  
             end
        end
    end

 Tr
vm
v
V(i)=sum(v(i))/sum(xm(i));
end
disp(V)

[Jan]

The question is not clear to me yet. What does " reuse that first loop( j ) again within the statements" mean?

What is the purpose of loops over one value? Replace "for i=1" by "i=1;". Nested loops with the same loop counter are confusing only. It is too hard to guess, what you want the code to do.

[GAGANDEEP KAUR]

Sorry for inconvinence. Actually I need to calculte the value of 'V' at every temperature given as input and for every temperature data have to use three set of values of other parameters(say Vc, Zc, Tc etc.) in loop.

For one temperature value code is written like this now I want to extend it to an array of temperature inputs

%%Calculate molar volume of solvent mixture

%xm=composition of species in solution

%Vc=critical volume of species

%vm=molar volume of species

%Tr=reduced temperature of species

%T=temperature of solution mixture

%V= molar volume of micture

Vc= [121.90 55.9 155];

Zc= [0.287 0.229 0.265];

Tc= [423.85 647.1 819.15];

xm= [0.1 0.2 0.2];

vm=[0 0 0];

v=[0 0 0];

Tr=[0 0 0];

T=473;..............................................................

if (T<=423.85)

for i=1:3

Tr(i)=T/Tc(i);

vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));

v(i)=xm(i)*vm(i);

end

elseif (423.85<T)&&(T<=647.1)

for i=1

T= 423.85;

Tr(i)=T/Tc(i);

vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));

v(i)=xm(i)*vm(i);

for i=2:3

Tr(i)=T/Tc(i);

vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));

v(i)=xm(i)*vm(i);

end

end

elseif (647.1<T)&&(T<=819.15)

for i=1

T=423.85;

Tr(i)=T/Tc(i);

vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));

v(i)=xm(i)*vm(i);

for i=2

T=647.1;

Tr(i)=T/Tc(i);

vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));

v(i)=xm(i)*vm(i);

for i=3

Tr(i)=T/Tc(i);

vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));

v(i)=xm(i)*vm(i);

end

end

end

end

Tr

vm

v

V=sum(v)/sum(xm);

disp(V)

Answer 1

[Jan]

Cleanup the strange nested loops over scalars:

        for i=1
                T= 423.85;
                 Tr(i)=T/Tc(i);
                 vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
                  v(i)=xm(i)*vm(i); 
                for i=2:3
                 Tr(i)=T/Tc(i);
                 vm(i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
                  v(i)=xm(i)*vm(i);
                end
        end

This is a waste of time only, because you calculate exactly the same in both loops. So simply write:

        T = 423.85;
        for i = 1:3
           Tr(i) = T/Tc(i);
           vm(i) = Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
           v(i)  = xm(i)*vm(i);
        end

Or even without a loop:

    Tr = T ./ Tc;
    vm = Vc .* (Zc .^ ((1 - Tr) .^ 0.286));
    v  = xm .* vm;

The complete shown code can be simplified to:

Tv = [min(T, 423.85), min(T, 647.1), min(T, 647.1)];
Tr = T ./ Tc;
vm = Vc .* (Zc .^ ((1 - Tr) .^ 0.286));
v  = xm .* vm; 
V  = sum(v) / sum(xm);
disp(V)

No loops, no different branches, no "for i=1".