Sum of series program logical error

This program is supposed to calculate:

S= 2! -4! +6! -8! …..n terms

public class Series7

{

int sum, i, term, j, prod;

public void main(int n)

{

sum = 0;

term=2;

prod = 1;

for (i=1;i<=n;i++)

{

for(j=term;j>1;j--)

prod *= j;

term += 2;

if(i%2==0)

sum -= prod;

else

sum += prod;

}

System.out.println("The sum is "+sum);

}

}

Re: Sum of series program logical error

What does it do instead? Do you have a question?

Re: Sum of series program logical error

You have a ton of problems with syntax but that aside your logic problems stems from messy seperation of what each loop does.

Outer loop: adds 2 to the term, adds the fac result to the output sum.

Inner loop: Fac'ing the term.

Im not sure you are fac'ing right. Try using recursion as it brings beautiful solution to fac'ing.

Code java:

public void myFunc(int n){
int sum = 0;
int term = 2;
for (int i = 1; i <= n ; i++){
if(i % 2 == 0)
{
sum -= myFac(term);
} else {
sum += myFac(term);
}
term += 2;
}
System.out.println(sum);
}

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