MATLAB: Help to solv a equation with iteration

iteration solv

I need help, how do i make a code in matlab for iterate the following eq:
x=0.46-0.5*cos(3.14*(y/d))+0.004*cos(2*3.14*(y/d))
where y is the only unknown constant? i know the value of x and d.

Best Answer

hi Clauss,
there are many ways to solve the equation, but with iterations i have few ideas : there is a method called Bisection :
 d=1.3; % I SUPPOSED d=1.3
 f=@(y) 0.46-0.5*cos(3.14*(y/d))+0.004*cos(2*3.14*(y/d))
 format long
 eps_abs = 1e-5;
 eps_step = 1e-5;
 a = 70.0; % Initial Guess to your function such that f(a)>0.
 b = 78.0; % Initial Guess to your function such that f(b)<0.
 while (b - a >= eps_step || ( abs( f(a) ) >= eps_abs && abs( f(b) )  >= eps_abs ) )
    c = (a + b)/2;
    if ( f(c) == 0 )
       break;
    elseif ( f(a)*f(c) < 0 )
       b = c;
    else
       a = c;
    end
end
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