Sorry for the reply. I did not get your message until now. I was wondering if there was a way to develop floating-point mathematics package within a module. I was wondering if some of your work on bit twiddling floating - point numbers could be provided to me!!! Thanks. David Blubaugh
________________________________ From: Jeff Goldfinkle [mailto:[EMAIL PROTECTED] Sent: Monday, April 28, 2008 2:10 PM To: Blubaugh, David A. Subject: Re: Bit twiddling floating point numbers sure - go right ahead On Mon, Apr 28, 2008 at 8:17 PM, Blubaugh, David A. <[EMAIL PROTECTED]> wrote: Are you still out there? Can I still ask you about my question? thanks, David ________________________________ From: Jeff Goldfinkle [mailto:[EMAIL PROTECTED] Sent: Friday, March 07, 2008 1:04 AM To: Blubaugh, David A. Subject: Re: Bit twiddling floating point numbers Hi David Sure. I'm not sure what help I can be, but ask away. Jeff On Thu, Mar 6, 2008 at 11:25 PM, Blubaugh, David A. <[EMAIL PROTECTED]> wrote: Jeff, Hello. This idea or representing a float with long seems to be extremely interesting. I am currently utilizing the MyHDL environment to map algorithms to hardware. May I ask you more questions in order to map integer mathematics to emulate floating -point mathematics, in order to maybe develop efficient pseudo-floating-point hardware?? Thanks, David Blubaugh -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Thursday, March 06, 2008 4:01 PM To: python-list@python.org Subject: Re: Bit twiddling floating point numbers On Mar 6, 11:00 am, Bryan Olson <[EMAIL PROTECTED]> wrote: > Mark Dickinson wrote: > > Jeff Goldfin wrote: > >> I can pack and unpack a float into a long e.g. > >> struct.unpack('I',struct.pack('f',0.123))[0] > >> but then I'm not sure how to work with the resulting long. > > >> Any suggestions? > > > One alternative to using struct is to use math.ldexp and math.frexp: > > >>>> m, e = frexp(pi) > >>>> m > > 0.78539816339744828 > >>>> e > > 2 > >>>> int(m*2**53) > > 7074237752028440L > > > Then you can do your bit twiddling on int(m*2**53), before using > > ldexp to 'repack' the float. > > Ah, those are handy. Jeff described his problem: "In particular, I > would like to round my float to the n most significant bits." > I think this works: > > from math import frexp, ldexp, floor > > def round_mantissa(x, nbits): > shifter = 1 << nbits > (m, e) = frexp(x) > m = floor(m * shifter + 0.5) / shifter > return ldexp(m, e) > > -- > --Bryan Thanks for the help - your function seems to fit the bill even better than gmpy since I don't need an external module. In my case I'll use m = floor(m * shifter) / shifter instead of m = floor(m * shifter + 0.5) / shifter Jeff This e-mail transmission contains information that is confidential and may be privileged. It is intended only for the addressee(s) named above. If you receive this e-mail in error, please do not read, copy or disseminate it in any manner. If you are not the intended recipient, any disclosure, copying, distribution or use of the contents of this information is prohibited. Please reply to the message immediately by informing the sender that the message was misdirected. After replying, please erase it from your computer system. Your assistance in correcting this error is appreciated. This e-mail transmission contains information that is confidential and may be privileged. It is intended only for the addressee(s) named above. If you receive this e-mail in error, please do not read, copy or disseminate it in any manner. If you are not the intended recipient, any disclosure, copying, distribution or use of the contents of this information is prohibited. Please reply to the message immediately by informing the sender that the message was misdirected. After replying, please erase it from your computer system. Your assistance in correcting this error is appreciated.
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