Loop question in code

I have a code which runs a certain number of calculations and then displays the answer.

However what I want to do is tell the code to check with the vector created is a certain size, and if this check fails it goes back to a certain point in the code, adding a number to an initial variable and starting again.

I was wondering if there was a way to do this with something like a 'return' function

I don't think if or for loops are what I want

I have included my code as an example

%%Calculation to assess water temperature around the plant
C_pd = Specific_Heat(T_d,X_d);
C_pb = Specific_Heat(T_b,X_b);
e = 0.01;
f = 0.001;
k = 60;         % Initial Minimum Value of T_f
l = 70;         % Initial Maximum Value of T_F
m = 30;         % Initial Minimum Value of T_o
n = 40;         % Initial Maximum Value of T_f
i = 1;
Time1 = clock;
w = 3.6;          % Error Factor

Return to here

for z = 1:3
    g = 1/10^w;
    for T_f = k:e:l
        C_pf = Specific_Heat(T_f,X_f);
        a = M_f*C_pf*(T_f-T_cw);
        for T_o = m:f:n
            b = M_d*C_pd*(T_d-T_o) + M_b*C_pb*(T_b-T_o); 
            if abs(a-b)<g
                T(1,i) = T_f; 
                T(2,i) = T_o;
                i=i+1;
            end
        end  
    end
    k = min(T(1,:));
    l = max(T(1,:));
    m = min(T(2,:));
    n = max(T(2,:)); 
    e=e/10;
    f = f/10;
    w=w+1;
end

Time2 = clock;
size(T);

if size(T) == [2 1];
    disp('T_f (68) = ')
    disp(T(1,:))
    disp('T_o (36) = ')
    disp(T(2,:))
    if T(1,:) == 68             % Error check
    else
         T_fdiff =  T(1,:) - 68
    end
    if T(2,:) == 36
    else
     T_odiff = T(2,:) - 36
    end
else
    disp(size(T))
    w = w + 0.01;

Loop from here

 end
  clock = etime(Time2,Time1)

Any thoughts?

Thanks in advance

[Walter Roberson]

There is no such thing as an "if loop". There are for loops, while loops, and if statements.

Answer 1

[Sean de Wolski]

No MATLAB does not have a goto command. This is a good place to start:

http://blogs.mathworks.com/loren/2007/07/23/goto-humor/

What do you want by loop from here. What do you want the code to do? Since it looks like you're dealing with clock, perhaps a timer is a good place to start. Timers allow you to execute code repeatedly, at fixed intervals, n number of times.

doc timer

[Thomas Humphrey]

I don't think I can restructure my code to include this. Unless I put the whole thing inside an IF loop which I don't think would be very good.

What i'm trying to do is an iteration of an equation that has 3 variables. This is done by splitting the equation into two separate equations and when they equal each other, the code reports to an array.

I then want to check this array has only 1 answer for the variables in it (as the code starts off with thousands) and then if it only has 1 answer the code displays the answer, if not it changes the input error conditional and retries the code again until only 1 answer is left.

at the moment if the code fails I am having to redo my input error conditionals until it works

[Sean de Wolski]

So put all of the code running the engine in a function and use a while-loop in another function (or script) to run the engine with varying inputs each time. The inputs can be calculated from either outputs or preset values.

[Thomas Humphrey]

Good idea, Is there not a simpler way though? Guess not.