Ininifty as the answer

[Logan Knecht]

I made this program to divide by N for each iteration of the while loop, and in doing so it would take the sum of every iteration and print it to the line, the only problem is that the answer I receive is this.

Sum is: Infinity

import java.io.*;
 
class Ch16Ex2
{
public static void main(String[] args)throws IOException
{
BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));

System.out.println("Enter N: ");
double N = Integer.parseInt(stdin.readLine());

double x = 0;
double y = 0;
int z = 0;
double sum = 0;

while (x < N)
{
y = (1.0)/z;
sum = sum + y;
x++;
z++;
}

System.out.println("Sum is: " + sum);
}
}    

If anyone knows why I'd love to know. Also, if anyone has any input on how to do this better too, I would love to know.

Thanks.

[vanlalhmangaiha khiangte]

You have initialise z=0

   
y = (1.0)/z; (anything divided by 0 is infinity)
sum = sum + y; (sum will always be infinity because y is infinity

Hope this helps ...

[Logan Knecht]

Ahahahah oh wow, what a stupid mistake.

[Rob Spoor]

I'd suggest turning x and N into ints. Check out this about some problems with floating point numbers.

[Campbell Ritchie]

Originally posted by Rob Prime:
I'd suggest turning x and N into ints.

But then make sure you are never dividing by 0!

[Rob Spoor]

The only division here is 1.0 by z, and z is already an int.

Or do you mean this as a warning for future references that any division with no floats or doubles will throw a ArithmeticException?

[Amit Ghorpade]

Originally posted by Campbell Ritchie
But then make sure you are never dividing by 0!

Yes that will lead to an exception.
But that brings up an question, why separate behavior for int and double?

[Amit Ghorpade]

Googled and found the answer here
[ August 13, 2008: Message edited by: Amit Ghorpade ]

[Campbell Ritchie]

Originally posted by Rob Prime:
The only division here is 1.0 by z, and z is already an int.

Or do you mean this as a warning for future references that any division with no floats or doubles will throw a ArithmeticException?

Sorry for delay: yes, I meant a warning against the ArithmeticException.