Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » sci.math.* » sci.math

Topic: Fast exponent and logarithm, given initial estimate
Replies: 29   Last Post: Nov 8, 2004 2:31 AM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Glen Low

Posts: 41
Registered: 12/13/04
Re: Fast exponent and logarithm, given initial estimate
Posted: Oct 19, 2004 10:22 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply


> In case the exponentials are of some limited range (say -0.5 to 0.5 or
> -10 to 10 for example), and if some lookup tables are allowed, one
> could use static lookup tables of the exponent function that cover the
> individual decimals of the exponentials. Example: to calculate exp(7.345)
> one needs exp(7), exp(0.3), exp(0.04) and exp(0.005) (all of these
> are obviously to be multiplied to get the result), and these could be
> provided in lookup tables that store
> [exp(0)],exp(1),exp(2),..exp(10)
> exp(0.1),exp(0.2),..exp(0.9)
> exp(0.01),exp(0.02),..exp(0.09)

The problem with lookup tables is that SIMD code tends to fare badly
with extensive memory loads. Indeed given the current state of CPU
development, most CPU's now are much faster than memory, so
calculation is often faster than loading from memory. Of course if the
lookup tables are small and would fit into L1 or L2 cache, they could
be used.

This is meant to be a general purpose exponentiation routine as well.

Cheers
Glen low, Pixelglow Software
www.pixelglow.com



Date Subject Author
10/18/04
Read Fast exponent and logarithm, given initial estimate
Glen Low
10/18/04
Read Re: Fast exponent and logarithm, given initial estimate
Jeremy Watts
10/19/04
Read Re: Fast exponent and logarithm, given initial estimate
Peter Spellucci
10/19/04
Read Re: Fast exponent and logarithm, given initial estimate
Glen Low
10/18/04
Read Re: Fast exponent and logarithm, given initial estimate
bv
10/19/04
Read Re: Fast exponent and logarithm, given initial estimate
Glen Low
10/19/04
Read Re: Fast exponent and logarithm, given initial estimate
George Russell
10/19/04
Read Re: Fast exponent and logarithm, given initial estimate
Glen Low
10/20/04
Read Re: Fast exponent and logarithm, given initial estimate
George Russell
10/20/04
Read Re: Fast exponent and logarithm, given initial estimate
Glen Low
10/21/04
Read Re: Fast exponent and logarithm, given initial estimate
Christer Ericson
10/21/04
Read Re: Fast exponent and logarithm, given initial estimate
Glen Low
10/22/04
Read Re: Fast exponent and logarithm, given initial estimate
Christer Ericson
10/19/04
Read Re: Fast exponent and logarithm, given initial estimate
Martin Brown
10/19/04
Read Re: Fast exponent and logarithm, given initial estimate
Glen Low
10/19/04
Read Re: Fast exponent and logarithm, given initial estimate
Richard Mathar
10/19/04
Read Re: Fast exponent and logarithm, given initial estimate
Glen Low
10/20/04
Read Re: Fast exponent and logarithm, given initial estimate
Gert Van den Eynde
10/20/04
Read Re: Fast exponent and logarithm, given initial estimate
Glen Low
10/20/04
Read Re: Fast exponent and logarithm, given initial estimate
Richard Mathar
10/21/04
Read Re: Fast exponent and logarithm, given initial estimate
Gert Van den Eynde
10/21/04
Read Re: Fast exponent and logarithm, given initial estimate
bv
10/22/04
Read Re: Fast exponent and logarithm, given initial estimate
Glen Low
10/22/04
Read Re: Fast exponent and logarithm, given initial estimate
Peter Spellucci
10/22/04
Read Re: Fast exponent and logarithm, given initial estimate
Glen Low
10/23/04
Read Re: Fast exponent and logarithm, given initial estimate
bv
10/24/04
Read Re: Fast exponent and logarithm, given initial estimate
Gert Van den Eynde
10/25/04
Read Re: Fast exponent and logarithm, given initial estimate
Peter Spellucci
10/20/04
Read Re: Fast exponent and logarithm, given initial estimate
Gert Van den Eynde
11/8/04
Read Re: Fast exponent and logarithm, given initial estimate
Glen Low

Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.