MATLAB: Fsolve

fasterfsolve

Is there a way to accelerate the fsolve function, with the least lost of precision possible. In:

beta(n+1)=fsolve(F,beta(n))

Best Answer

preallocate beta

beta = zeros(nmax+1,1);
beta(1) = beta_of_1;
for ii = 1:nmax
 beta(ii+1) = fsolve(F,beta(ii));
end

EDIT more stuff:

You calculate:

'sqrt((Ko^2-(x)^2))*b': 4x
'sqrt((Ko^2*Ed-(x)^2))*a': 4x
the bessel functions multiple times a pop.

Turn your function handle into a function. Make each of these calculations once, then use them multiple times.

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MATLAB: How to plot this implicit function

Try symbolic expression

clc,clear
alpha=1.5; A=0.0207; gamma=0.25;
syms beta eps
x = (beta-alpha*(beta-gamma)+sqrt((beta-alpha*(beta-gamma)).^2+4*alpha*beta*gamma*A))./(2*beta);
y =  x.*(1-x).*beta/gamma;
t =  -x+x.*y.*(alpha-eps*beta)./((A+x+y).^2);
d =  eps*beta.*x.*y.*(x.^2+(A+x).*x+A*alpha)./((A+x+y).^3);
    % convert symbolic expression to function handle
F = matlabFunction(t.^2 - d,'vars',[beta eps]);
ezplot(F,[0,1,0,1]);

MATLAB: Globalsearch not working for a function file.

Lets start by reading the error message: "Supplied objective function must return a scalar value"

So, the objective function must return a scalar value. A scalr has size 1x1. Lets run the objective function and see if it returns a scalar value:

>> X = Trans_eqn_taperedfiber([1/3,2/3]);
>> size(X)
ans =
         1       49000

Is 1x49000 scalar? No. So the problem is your function returns a vector, which both the documentation and the error message clearly state is not allowed. You need to change your function to return a scalar value. Also note that you could generate a, b, and c without the loop using simpler vectorized code.

Best Answer

Related Solutions

MATLAB: How to plot this implicit function

MATLAB: Globalsearch not working for a function file.

Related Question