Sum functions code in matlab

I wrote this matlab codes but I fear something might be wrong.

function F = myfun (x) 

format long

syms beta alpha lambda omega n I

n=100;

F1=n-symsum(beta*x(i)^alpha*exp(lambda*x(i)),1,n)-2*symsum(beta*omega*x(i)^alpha*exp(-beta*x(i)^alpha*exp(lambda*x(i))+lambda*x(i))*(1-omega*exp(-beta*x(i)^alpha*exp(lambda*x(i))))^(-1),1,n);

F2=symsum(log(x(i)),1,n)+symsum(1/(alpha+lambda*x(i)),1,n)-symsum(beta*x(i)^alpha*exp(lambda*x(i))*log(x(i)),1,n)-2*symsum(alpha*omega*x(i)^alpha*exp(-beta*x(i)^alpha*exp(lambda*x(i))+lambda*x(i))*log(x(i))*
(1-omega*exp(-beta*x(i)^alpha*exp(lambda*x(i))))^(-1),1,n);

F3=symsum(x(i)/(alpha+lambda*x(i)),1,n)-symsum(beta*x(i)^(alpha+1)*exp(lambda*x(i)),1,n)-symsum(x(i),i,n)--2*symsum(beta*omega*x(i)^(alpha+1)*exp(-beta*x(i)^alpha*exp(lambda*x(i))+lambda*x(i))*(1-omega*exp(-beta*x(i)^alpha*exp(lambda*x(i))))^(-1),1,n);

F4=n/(1-omega)-2*syms(exp(beta*x(i)^alpha*exp(lambda*x(i)))*(1-omega*exp(-beta*x(i)^alpha*exp(lambda*x(i))))^(-1),1,n);

I wish to know if I am correct with the this matlab codes and the look of each function mathematically.

Thank you

Answer 1

[Walter Roberson]

No, that code cannot be correct, as it tries to index with the variable "i" that you have not defined. The default value for the variable named "i" happens to be sqrt(-1) which is something you cannot index by.

You should be using

syms i

and listing i in your symsum(), in the form

symsum(EXPRESSION, i, 1, n)

However! A recent posting explored that you cannot index by a symbolic variable. So you should not be using symsum(). You should be using regular sum()

For example,

symsum(beta*x(i)^alpha*exp(lambda*x(i)),1,n)

but

sum(beta .* x.^alpha .* exp(lambda .* x))