Please need help!! How to write this equation in terms of code?

Answer 1

[Walter Roberson]

x = 1 : L;
px = arrayfun(@p, 1:L);
ex = 1/L * sum(px .* x) / sum(px);

If p is vectorized then you can use

x = 1 : L;
px = p(x);
ex = 1/L * sum(px .* x) / sum(px);

Answer 2

[Faisal Muhammad]

p(x)=1+x^2    % some function

for x=1:L   
   ex=1/L*((p(x)*x)/(p(x))
end

By the way the function can be reduced by canceling p(x)

[Abdullah]

thanks a lot Brother Faisal

[Walter Roberson]

This is incorrect.

[Faisal Muhammad]

Abdullah, Walter is right. Please check his solution.