How to calculate the largest real number in IEEE double and single precision representation.
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How do you calculate (in your own way) the largest real number in IEEE double and single precision representations wihtout using realmax('single') and realmax('double')? thank you!
2 Kommentare
Matt Kindig
am 15 Mai 2013
Wikipedia gives a pretty good overview of how to do so in its article:
I happened to have been reading this article just today.
James Tursa
am 15 Mai 2013
Using just floating point operations? Or allowing for bit manipulation and type casting?
Antworten (1)
Jan
am 15 Mai 2013
Bearbeitet: Jan
am 15 Mai 2013
Using the bit-patterns defined e.g. here http://docs.oracle.com/cd/E19957-01/806-3568/ncg_math.html and a typecast should be sufficient. Because IEEE754 is a convention, there is nothing wrong with using the bit-patterns defined in this convention directly.
[EDITED] What about pow2(2 - eps, 1023)? Does this reply the correct answer?
2 Kommentare
José-Luis
am 15 Mai 2013
Bearbeitet: José-Luis
am 15 Mai 2013
It should give the correct answer since that is the formula invoked by realmax. Without using eps:
pow2(1 + (1 - 2^-52),1023) == realmax
Or even without pow2:
(1 + (1 - 2^-52))*2^1023 == realmax
Speedwise it might not be optimal but William seemed reluctant to use built-in functions.
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