How to implement a function within another one ?

Hi, I'd like to use the bisection method to find the root of a function "Fetoile" The method works but I have to iterate it for some values of a parameter "i". The problem is, the bisection function does not use "i".

Here is the code that gives me the results for "Fetoile" :

    function Fetoile = q4(v)

   % datas

    vitesse_rotation= [83.7758040957278, 119.587013890941, 155.398223686155, 191.209433481369, 227.020643276582, 262.831853071796, 298.643062867009, 334.454272662223, 370.265482457437, 406.07669225265, 441.887902047864, 477.699111843078, 513.510321638291, 549.321531433505, 585.132741228718, 620.943951023932, 656.755160819146, 692.566370614359, 728.377580409573, 764.188790204786]

    couple=[206.41064280052, 243.796265372056, 256.741969803922, 258.849308707433, 255.11836152428, 247.801181783381, 238.039957653591, 226.445249315901, 213.320493034029, 198.699623003111, 181.889713594511, 163.718280099678, 145.175662563345, 126.558747418095, 108.009552378088, 89.6025609484197, 71.3773301900352, 53.3538548851947, 35.5406860579882, 17.9395273160688]

    rho=1.2;
    S=2.28;
    Cx=0.31;
    mveh=1360;
    g=9.81;
    f0=0.0136;
    f2=4.*10.^(-7);
    ntrans=0.92;
    atrans=1.04;
    btrans=0.0025;
    R=0.31;
    i=[9.62,5.87,3.91,2.90,2.31];
    teta=0;

%end of datas

    for m = 1:5    

            Cmax=spline(vitesse_rotation,couple,i(m).*(v)/R);
            Faero = (1/2)*rho*S*Cx*(v).^2;
            Frlt = mveh*g*cos(teta)*(f0+f2*(v).^2);
            Fgrav = mveh*g*sin(teta);
            Fmotmax = ntrans*(i(m)/R)*Cmax;

            Fetoile = Faero + Frlt + Fgrav - Fmotmax;
            tabFetoile(m) = Fetoile;

    end %end of for loop
            disp('The results are :');
            disp(tabFetoile);

And here is the code for the bisection, I tried a loop on the values of "vmin" are values that I'm sure are negatives.

    function root = bishoz(f,vmin,vmax)

    resultat = [];

     for m = 1:5

         vmin=[6,9.5,13.5,16.5,19];
         vmax = 150;

        fvmin(m) = f(vmin(m));
        fvmax = f(vmax);

        if fvmax*fvmin(m) > 0

            disp('Valeurs de même signe.');

        else

            root = (vmax + vmin(m))/2;
            err = abs(f(root));

        end    

        while err > 1e-7

           if fvmax*f(root)<0 
               vmin(m) = root;
           else
               vmax = root;          
           end %end of if

       root = (vmax + vmin(m))/2;
       err = abs(f(root));

        end %end of while loop

        resultat(m)=root;

     end %end of for loop
     disp(resultat);

Answer 1

[John]

I read through your example and it looks like the language functionality you are looking for are nested functions. Please see this for more info http://www.mathworks.com/help/matlab/matlab_prog/nested-functions.html

[Martin Matin]

Thanks it seems like a good idea ! I was wondering something though.

When I call the function on MatLab, I have to call the first one, obviously. But in the help section, I don't find the syntax to make the first one call all the other. How should I write it ?

[John]

I do not understand what you are looking for Martin. Are you having problems calling the nested function from the outer main function?

It would help if you could provide a simple code example. That would help greatly. I have a feeling the answer you are looking for is close to hand. So please help us with a small example.

[Martin Matin]

It is okay, I finally did by making a script which I looped 5 times and I used a function handle to call q4.

Answer 2

[Xia]

Sorry I read your code twice but got lost. Would you please epitomize your question by a simple example? Maybe it'll be a little better for other guys to get into this question..

[Martin Matin]

I have a function that depends of "i" and "v" I have another function, bisecting the first one.

I want to make to make the bisection vary in terms of "i". But because the reach of "i" is only the first one, it doesn't work. It gives me 5 times the last value of "i".