It keeps giving me an error on line 4, saying I'm missing input arguments but I have everything defined?

function root = BisectionRoot(Q,q,R,F,z1,z2)
tol = 1e-6;
err = 1.0;
z = (z1 + z2)/2;
fz = Fun(Q,q,R,F,z);
fz1 = Fun(Q,q,R,F,z1);
fz2 = Fun(Q,q,R,F,z2);
while err > tol
    if fz1 < 0.0 & fz2 > 0.0
        if fz > 0.0
            z2 = z;
        else
            z1 = z;
        end
    elseif fz1 > 0.0 & fz2 < 0.0
        if fz < 0.0
            z2 = z;
        else
            z1 = z;
        end
    else
        disp('The given interval does not contain the root.');
        break;
    end
    z = (z1 + z2)/2;
    err = abs(z - z1);
    fz = Fun(Q,q,R,F,z);
    fz1 = Fun(Q,q,R,F,z1);
    fz2 = Fun(Q,q,R,F,z2);
end
root = z;
end

[Stephen23]

@Patrick: how exactly are you calling the function?

Most likely you are not calling it with all of its required input arguments, e.g. by clicking the big green "Run" button.

[Patrick]

@Stephen23 I just pressed the run button once I finished writing it, I don't know what input arguments I could be missing though. z1 and z2 are defined

[Stephen23]

"I just pressed the run button once I finished writing it"

So precisely what values do you expect MATLAB to use for the inputs Q,q,R,F,z1,z2 ?

[Patrick]

Q = 9.4e-6;

q = 2.4e-5;

R=0.1;

F=(Q*q*z) .*((1-z)./(sqrt(z.^2+R.^2)))/(2*epsilon);

epsilon= 0.885e-12;

So would I just add these values to my code?

Answer 1

[Torsten]

Q = 9.4e-6; 
q = 2.4e-5;
R=0.1;
epsilon= 0.885e-12;
F=@(z)(Q*q*z) .*((1-z)./(sqrt(z.^2+R.^2)))/(2*epsilon);
z1 = 0.5;
z2 = 2;
root = BisectionRoot(F,z1,z2)

function root = BisectionRoot(Fun,z1,z2)
tol = 1e-6;
err = 1.0;
z = (z1 + z2)/2;
fz = Fun(z);
fz1 = Fun(z1);
fz2 = Fun(z2);
while err > tol
    if fz1 < 0.0 & fz2 > 0.0
        if fz > 0.0
            z2 = z;
        else
            z1 = z;
        end
    elseif fz1 > 0.0 & fz2 < 0.0
        if fz < 0.0
            z2 = z;
        else
            z1 = z;
        end
    else
        disp('The given interval does not contain the root.');
        break;
    end
    z = (z1 + z2)/2;
    err = abs(z - z1);
    fz = Fun(z);
    fz1 = Fun(z1);
    fz2 = Fun(z2);
end
root = z;
end

[Patrick]

Thanks for clearing that up for me!