Relative error, absolute error, percentage error

[Nikoleto]

Hi all..I have a question to the visitors of that sweet site...
it is known that the relative error=absolute error/exact value
and so my question is if that exact value is equal to 0...is it possible to compute the relative error?
Thanks all!!! :wave:

[krtxmrtz]

Hi all..I have a question to the visitors of that sweet site...
it is known that the relative error=absolute error/exact value
and so my question is if that exact value is equal to 0...is it possible to compute the relative error?
Thanks all!!! :wave:
Simply put, the relative error tends to infinity but it's meaningless or rather useless.

It's a matter of interpretation: if you are computing the distance between 2 places, whcih is 100 km and your measurement yields 101 km, then you're off by 1%, relative error = (101-100)/100 = 0.01

If both places are the same so that the distance is 0, then any measurement producing a result other than 0 will be infinitely inaccurate.

[Nikoleto]

my question is what if my measurement yields 0 km not 101....shall i really put the relative error to tend to infinity?

[krtxmrtz]

my question is what if my measurement yields 0 km not 101....shall i really put the relative error to tend to infinity?
If your measurement is 0 over an actual distance of 100 km, then you're off by 100% (absolute error 100 km). If you measure 0 when the actual value is 0, then, again, the relative error has no meaning, it's computed as 0/0 which can be anything: 0/0 = x and this is satisfied by all real numbers x.

[System_Error]

This is a problem with relative error, but the likelyhood of encountering a situation where the exact value is zero, is almost zero...