Finding values of Lambert's W function for x>0

I have been struggling with this question and I think I have found an answer but I am not %100 sure. Can you check it please? First, I tried to define a Lambert function

function W = myLambert(a)
syms x;
f (x) = x*exp(x);
g = finverse(f);
double(g(a))
end

In the second part, it gives output for values greater than 0

clc;
clear all;
prompt = 'Enter the x value that is greater than 0 ';
q=input(prompt);
myLambert(q)

[Torsten]

finverse(f) will be MATLAB'S Lambert's W function, not yours ...

Answer 1

[Star Strider]

Solve this the same way you solved the Bessel function, this time without the loop.

Think of it this way: You want to find:

x = y.*exp(y)

for any ‘x’. Define ‘x’ and solve for ‘y’, using fzero.

[Koray Kocak]

I think I did it this time :)

function W = lambert(x)
f=@(y)y.*exp(y)-x % the root of this function at x is value of 
                  % the inverse of x*exp(x)
W=fzero(f,1e-6);

end

>> lambert(12)

f =

    function_handle with value:

      @(y)y.*exp(y)-x

ans =

      1.8628

[Star Strider]

You did.

That was the same result I got with this:

x = 12;
LW = lambertw(x);

f = @(y) y.*exp(y) - x;

y = fzero(f, 10);

for both ‘LW’ and ‘y’.

[Koray Kocak]

Thanks a lot!!!

[Star Strider]

My pleasure!