Re^3: Randomizing Large Integers

15 bit of the input or of the output?

I get the following behavior that lets me assume that 32 bit random integers work:

# perl -e 'printf "%010x\n", int rand 2**16'
00000052e2
# perl -e 'printf "%010x\n", int rand 2**32'
006f7ae0c5
# perl -e 'printf "%010x\n", int rand 2**64'
00ffffffff
[download]

i.e. rand 2**N seems to return a N bit random integer, up to N = 32 but not above.

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Re^4: Randomizing Large Integers by BrowserUk (Patriarch) on May 19, 2008 at 21:25 UTC
The 15-bit rand function is a Win32 Perl (MS CRT-based) problem. See Re^3: Rand Wackiness! and thread at A better rand() for Win32 for some further discussion. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply]
Re^4: Randomizing Large Integers by ikegami (Patriarch) on May 20, 2008 at 16:59 UTC
15 bit of the input or of the output? 15 bits of entropy. For a given argument, rand will only spit out 2¹⁵ different results (spread over the requested range).	[reply]