While loop does not repeat

Sorry about this long and silly code. I really need to know why this loop does not work properly. It is killing me. The code works just fine with one firm at a time, however, the loop only run for the first element in the "first_firm".

For example, without the "while i<=size(first_firm,1)" loop, load each firm by hand, the code works find. By adding the outside loop, I'm expecting that all firms in the "first_firm" matrix can be ran automaticly. However, it only runs the first one.

Therefore, my question is why does the loop always stop after running the first firm?

first_firm=[2502;2914;3382;4063;4452;4502;4523;4901;5108;6367;6902;6954;6971;
    7203;7267;7269;7270;7751;8035;8316;8766;8801;8830;9020;9021;9022;9432;9433;
    9735;9983;9984];
indf = 1;
while i <= size(first_firm,1)
    n_firm = first_firm(indf);
    load(['/pathname/',num2str(n_firm),'_P1_first_firm_before.mat']);
   
    P1(P1(:,8)==0,:)=[];
    P1_am = P1(P1(:,2)<=113001 & P1(:,2)>=85900,:);
    P1_pm = P1(P1(:,2)<=150000 & P1(:,2)>=122900,:);

    if P1_am(1,[3,4])~=0
        P1_am(1,:)=P1_am(2,:);
    end 

    if P1_pm(1,[3,4])~=0
        P1_pm(1,:)=P1_pm(2,:);
    end 
    P2=[P1_am;P1_pm];
    
    i=1;
    while i < size(P2,1)
        if P2(i,3)==0 && P2(i,4)==0
            I(i,:)=P2(i,:);

        elseif P2(i,3)~=0 && P2(i,4)~=0 && P2(i,8)==1
            I(i,:)=P2(i-1,:);
            I(i,6)=P2(i-1,6)-P2(i,4);

        elseif P2(i,3)~=0 && P2(i,4)~=0 && P2(i,8)==-1
            I(i,:)=P2(i-1,:);
            I(i,22)=P2(i-1,22)-P2(i,4);            
        end
        i=i+1; 
    end

    i=1;
    while i < size(I,1)
        if  I(i,3)~=0 && I(i,4)~=0
            I(i,:)=I(i-1,:);
        end 
        
        if  I(i,6)==0
            I(i,[5:18])=I(i,[7:20]);
            I(i,[19:20])=I(i+1,[19:20]);
            
        elseif I(i,22)==0
            I(i,[21:34])=I(i,[23:36]);
            I(i,[34:36])=I(i+1,[34:36]);
        end 
        i=i+1; 
    end

    I_am = I(I(:,2)<=113001 & I(:,2)>=85900,:);
    I_pm = I(I(:,2)<=150000 & I(:,2)>=122900,:);

    Price = [5:2:35];Volume = [6:2:36];
    ask_P = [5:2:19];bid_P = [21:2:35];
    ask_V = [6:2:20];bid_V = [22:2:36];

    mkt_odr_p_am = find(P1_am(:,3)~=0)-1;
    mkt_ord_p_pm = find(P1_pm(:,3)~=0)-1;
    
    i = 1;
    while i < size(I_am,1)

        if I_am(i, Price) == I_am(i+1, Price)
            I1(i, [1:4,Price]) = I_am(i, [1:4,Price]);
            I1(i, Volume) = I_am(i+1, Volume) - I_am(i, Volume);

        else
            I1(i, [1:4,Price]) = I_am(i+1, [1:4,Price]);
            I1(i, Volume) = 0;
            if sum(I_am(i, ask_P) > I_am(i+1, ask_P))>0
                I3 = find(I_am(i, ask_P) ~= I_am(i+1, ask_P));
                I1(i, ask_P(I3(1))) = I_am(i+1, ask_P(I3(1)));
                I1(i, ask_V(I3(1))) = I_am(i+1, ask_V(I3(1)));

            elseif sum(I_am(i, ask_P) < I_am(i+1, ask_P))>0
                I3 = find(I_am(i, ask_P) ~= I_am(i+1, ask_P));
                I1(i, ask_P(I3(1))) = I_am(i, ask_P(I3(1)));
                I1(i, ask_V(I3(1))) = -I_am(i, ask_V(I3(1)));

            elseif sum(I_am(i, bid_P) > I_am(i+1, bid_P))>0
                I3 = find(I_am(i, bid_P) ~= I_am(i+1, bid_P));
                I1(i, bid_P(I3(1))) = I_am(i, bid_P(I3(1)));
                I1(i, bid_V(I3(1))) = -I_am(i, bid_V(I3(1)));

            elseif sum(I_am(i, bid_P) < I_am(i+1, bid_P))>0
                I3 = find(I_am(i, bid_P) ~= I_am(i+1, bid_P));
                I1(i, bid_P(I3(1))) = I_am(i+1, bid_P(I3(1)));
                I1(i, bid_V(I3(1))) = I_am(i+1, bid_V(I3(1)));
            end
        end
        i = i+1;
    end
    I1(mkt_odr_p_am,:)=[];

    i = 1;
    while i < size(I_pm,1)
        if I_pm(i, Price) == I_pm(i+1, Price)
            I2(i, [1:4,Price]) = I_pm(i, [1:4,Price]);
            I2(i, Volume) = I_pm(i+1, Volume) - I_pm(i, Volume);

        else
            I2(i, [1:4,Price]) = I_pm(i+1, [1:4,Price]);
            I2(i, Volume) = 0;
            if sum(I_pm(i, ask_P) > I_pm(i+1, ask_P))>0
                I3 = find(I_pm(i, ask_P) ~= I_pm(i+1, ask_P));
                I2(i, ask_P(I3(1))) = I_pm(i+1, ask_P(I3(1)));
                I2(i, ask_V(I3(1))) = I_pm(i+1, ask_V(I3(1)));

            elseif sum(I_pm(i, ask_P) < I_pm(i+1, ask_P))>0
                I3 = find(I_pm(i, ask_P) ~= I_pm(i+1, ask_P));
                I2(i, ask_P(I3(1))) = I_pm(i, ask_P(I3(1)));
                I2(i, ask_V(I3(1))) = -I_pm(i, ask_V(I3(1)));

            elseif sum(I_pm(i, bid_P) > I_pm(i+1, bid_P))>0
                I3 = find(I_pm(i, bid_P) ~= I_pm(i+1, bid_P));
                I2(i, bid_P(I3(1))) = I_pm(i, bid_P(I3(1)));
                I2(i, bid_V(I3(1))) = -I_pm(i, bid_V(I3(1)));

            elseif sum(I_pm(i, bid_P) < I_pm(i+1, bid_P))>0
                I3 = find(I_pm(i, bid_P) ~= I_pm(i+1, bid_P));
                I2(i, bid_P(I3(1))) = I_pm(i+1, bid_P(I3(1)));
                I2(i, bid_V(I3(1))) = I_pm(i+1, bid_V(I3(1)));
            end
        end
        i = i+1;
    end
    I2(mkt_ord_p_pm,:)=[];
    
    I=[I1;I2];
   
    
    save(['/pathname/',num2str(n_firm),'_P2_first_firm_before.mat'],'P2')
    save(['/pathname/',num2str(n_firm),'_I1_first_firm_before.mat'],'I')

    indf = indf+1
    
end

Answer 1

[Jan]

The code should not work at all, because i is not defined before

while i <= size(first_firm,1)

But then Matlab assumes you mean the imaginary unit.

After

indf = 1;

and the trailing

indf = indf+1

I guess you meant:

while indf <= size(first_firm,1)

A for loop would be nicer:

for indf = 1:numel(first_firm)
    ...
end

By the way, a:b is a vector already and additional square brackets can slow down the execution:

% I(i,[5:18])=I(i,[7:20]);
I(i, 5:18) = I(i, 7:20);   % Faster!

[Shuxin Yang]

Thank you very much for your reply.

In fact, while i <= size(first_firm,1) was a typo of this question and it is indf in the original code.

Somehow the code works without changes. I have no idea why it did not work at the first time.

I tried your suggestion of for loop and it is indeed better. Thank you very much.