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Re: [avr-libc-dev] Re: Add items on TODO
From: |
Joerg Wunsch |
Subject: |
Re: [avr-libc-dev] Re: Add items on TODO |
Date: |
Wed, 30 Oct 2002 13:19:33 +0100 |
User-agent: |
Mutt/1.2.5i |
As Theodore A. Roth wrote:
[the asin() problem]
> My investigation seemed lead to there not being a clear
> understanding of the format of the floats. gcc uses ieee format
> floats so 1.0 looks like 0x3f800000, while the asin() implementation
> seems to think 1.0 is 0x7f000000.
Nope. asin() uses 0x3f800001 to denote a ``number slightly larger
than 1.0''. This is correct. The 0x7f you're seeing atop is masking
out the sign of the operand. The 0x3f800001 is micro-optimized and
not displayed completely, i. e. the third byte is taken from
__zero_reg__ instead (obfuscated as "rT1c" in the source).
So the problem is indeed that the implemented algorithm becomes fairly
inaccurate for small numbers.
--
J"org Wunsch Unix support engineer
address@hidden http://www.interface-systems.de/~j/
- [avr-libc-dev] Re: Add items on TODO, Theodore A. Roth, 2002/10/22
- Re: [avr-libc-dev] Re: Add items on TODO, Joerg Wunsch, 2002/10/23
- Re: [avr-libc-dev] Re: Add items on TODO,
Joerg Wunsch <=
- Re: [avr-libc-dev] Re: Add items on TODO, E. Weddington, 2002/10/30
- Re: [avr-libc-dev] Re: Add items on TODO, Joerg Wunsch, 2002/10/30
- Re: [avr-libc-dev] Re: Add items on TODO, E. Weddington, 2002/10/30
- Re: [avr-libc-dev] Re: Add items on TODO, Joerg Wunsch, 2002/10/30
- Re: [avr-libc-dev] Re: Add items on TODO, E. Weddington, 2002/10/30
- Re: [avr-libc-dev] Re: Add items on TODO, Joerg Wunsch, 2002/10/30
- Re: [avr-libc-dev] Re: Add items on TODO, E. Weddington, 2002/10/30
- Re: [avr-libc-dev] Re: Add items on TODO, Theodore A. Roth, 2002/10/30
- Re: [avr-libc-dev] Re: Add items on TODO, E. Weddington, 2002/10/30