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 Comments
Matt Kindig
on 15 May 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
on 15 May 2013
Using just floating point operations? Or allowing for bit manipulation and type casting?
Answers (1)
Jan
on 15 May 2013
Edited: Jan
on 15 May 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 Comments
José-Luis
on 15 May 2013
Edited: José-Luis
on 15 May 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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