Need appropriate for loop with if condition

I need to calculate V with some T value conditions, if T satisfies first condition I got to get desired values but if T lies in second or third condition, I am not able to represent the command appropriately. I will be grateful if I could get some correction. What I am trying to do is, say for second condition [elseif (423.85<T(j))&&(T(j)<=647.1)] for i=1, I made T values constant at 423.85, but for i=2 and i=3(here I means it should take up 2nd and 3rd valuesof Vc, Zc, Tc in loop as normal) I have written statements to be solved with given T(j). Similarly if third condition is true T is made constant, for i=1 T=423.85, for i=2, T=647.1 and for i=3 it should solve for given T(j)

function [V] = SolventMV(T,xm)
    
    xm=[ 0.000006250 0.000006199  0.000004616;
        0.4313 0.4315   0.4315;
        0.2714 0.2681 0.2653];
    T=[394.15; 399.15; 500.15 ];
    Vc= [121.90 55.9 155];
    Zc= [0.287 0.229 0.265];
    Tc= [423.85 647.1 819.15];
    N=length(T);
    V=zeros(N,1);
    vm=zeros(N,3);
    v=zeros(N,3);
    Tr=zeros(N,3);
    
    for j=1:N
        
        if (T(j)<=423.85)
            for i=1:3
                Tr(j,i)=T(j)/Tc(i);
                vm(j,i)=Vc(i)*(Zc(i)^((1-Tr(j,i))^0.286));
                v(j,i)=xm(i,j)*vm(j,i);
                V(j)=sum(v(j,:))/sum(xm(:,j));
            end
        elseif (423.85<T(j))&&(T(j)<=647.1)
            for i=1
                Tr(i)=423.85/Tc(i);
                vm(j,i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
                v(j,i)=xm(i,j)*vm(j,i);
                for i=2:3
                    Tr(i)=T(j)/Tc(i);
                    vm(j,i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
                    v(j,i)=xm(i,j)*vm(j,i);
                end
                V(j)=sum(v(j,:))/sum(xm(:,j));
            end
        elseif (647.1<T(j))&&(T(j)<=819.15)
            for i=1
                Tr(i)=423.85/Tc(i);
                vm(j,i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
                v(j,i)=xm(i,j)*vm(j,i);
                for i=2
                    Tr(i)=647.1/Tc(i);
                    vm(j,i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
                    v(j,i)=xm(i,j)*vm(j,i);
                    for i=3
                        Tr(i)=T/Tc(i);
                        vm(j,i)=Vc(i)*(Zc(i)^((1-Tr(i))^0.286));
                        v(j,i)=xm(i,j)*vm(j,i);
                    end
                end
                V(j)=sum(v(j,:))/sum(xm(:,j));
            end
        end
        
        Tr
        vm
        v
        V
    end
end

[per isakson]

You use the same index in nested for-loops

for i = 1
    for i = 2
        for i = 3
        end
    end
end

Is that by purpose? It might work, but it's definitely not recommended.

[GAGANDEEP KAUR]

Actually I got to know my mistake of using same index but how to correct it for the pupose, I am not getting idea

[VBBV]

%if true
for i = 1:3 
 if i  == 1
   % your code
 elseif i == 2
   % your code 
 elseif i  == 3
   % Your code 
 end
end

You can use this for loop structure inside the if else since you have different code lines for each iteration of variable i

[VBBV]

This way you get rid of multiple for loops

[GAGANDEEP KAUR]

It is considering an invalid matlab syntax in case of looping

[VBBV]

What error do you get?

[GAGANDEEP KAUR]

It is showing invalid use of operator. Actually i think omitting loops might not work for me as I need to calculate V calculated with all the components 1,2,3, but on 1,2,3 conditions apply. As if, 3rd condition is true for i=1,T=Tc(1) ,constant,for i=2,T=Tc(2), constant and for i=3, T=T(j).

1 2 3

Vc= [121.90 55.9 155];

Zc= [0.287 0.229 0.265];

Tc= [423.85 647.1 819.15];

N=length(T);

V=zeros(N,1);

vm=zeros(N,3);

v=zeros(N,3);

Tr=zeros(N,3);

for j=1:N

if (T(j)<=423.85)

for i=1:3

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

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

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

V(j)=sum(v(j,:))/sum(xm(:,j));

end

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

for i==1

Tr(i)=423.85/Tc(i);

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

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

for i==2:3

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

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

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

end

V(j)=sum(v(j,:))/sum(xm(:,j));

end

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

for i==1

Tr(i)=423.85/Tc(i);

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

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

for i==2

Tr(i)=647.1/Tc(i);

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

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

for i==3

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

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

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

end

end

V(j)=sum(v(j,:))/sum(xm(:,j));

end

end

Tr

vm

v

V

end

end

xm=[0.5096 0.5092 0.5087;

0.0963 0.0964 0.0965;

0.3941 0.3944 0.3948];

>> T=[394.15 399.15 404.15 ];[V]=SolventMV(T,xm)

Error: File: SolventMV.m Line: 29 Column: 14

Invalid use of operator.

[VBBV]

Note that the operator '==' is logical equivalent to equal for checking sameness. It can't be used in for loop iterative index as you have done in the program.

Look into the program structure in my earlier comment. It should work fine without errors.