Thread: how to avoid rounding?

Hello, people. I need help.

I need to write a program in C that uses a function to calculate the sum of all fractions 1/(a^4) for "a" values from 1 to x(which is scanf'ed), with 6 digits after the comma. I wrote the code:

Code:

#include <stdio.h>
float f;
int function(int x) {
	int a=1;
	float e;
	while(a<=x)
	{
		e=1/(a*a*a*a);
		f=f+e;
		a++;
	}
	return(f);
}

The code seems to work (it works if I remove "1/", it DOES sum up all a^4's), but in the aforementioned case the answer is always 1.000000. The program seems to automatically round all values of 1/a*a*a*a to zero for a>1. How do I avoid this?

Thanks in advance

you need float or double to do division without the answer being truncated. So, you could either declare "a" to be "float" or double, or cast a^4 to float or double. And "1" need to be "1.0" to avoid implicit cast.

Originally Posted by Eldente

Thanks for your quick answers, my compiler (Visual Studio '10) didn't scream at all, but changing it to float function(int x) did do the trick!

Thanks again!

It wouldn't give you the error because it does implicit conversion to int for you.