floating-pointprecisionieee-754128-bit

Is 128-bit "long-float" useful?

I realized the other day that most common lisp had 128-bit "long-floats". As a result, the most positive long float is:

8.8080652584198167656 * 10^646456992

while the most positive double float is 1.7976931348623157 * 10^308, which is pretty big already.

I wanted to know whether anyone had ever needed a number bigger than 1.7976931348623157 * 10^308, and if so, in which condition?

Do you feel it is useful to have by default in a programming language?

Is the precision of a 64-bit double float not enough in some circumstances? I would love to hear use-cases.

Solution

  • Scientists use this kind of stuff - and occasionally arbitrarily sized integers/floats/decimals.

    For you, 32-bit or 64-bit is usually enough.

    See also:

    http://en.wikipedia.org/wiki/Arbitrary-precision_arithmetic