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Re: [avr-gcc-list] Problem with asin() and acos()
From: |
Joerg Wunsch |
Subject: |
Re: [avr-gcc-list] Problem with asin() and acos() |
Date: |
Wed, 2 Oct 2002 10:45:42 +0200 (MET DST) |
address@hidden wrote:
> In a posting on the avr-gcc mailing list july 27th
> Jamie Morken (address@hidden) describes
> exactly the same problem.
> What strokes me in Jamie's desciption is that he gets
> the same (wrong) result as I did:
Then it's probably really at fault.
acos() calls asin(), and just adds Pi/2 to the result, so it's no
surprise that both are incorrect. Maybe this approach is error-prone
for small numbers?
At a glance, i don't quite understand the algorithm used. You might
want to have a look at the implementation of both functions under
http://savannah.nongnu.org/cgi-bin/viewcvs/*checkout*/avr-libc/avr-libc/libm/fplib/cos.S?rev=HEAD&content-type=text/plain
http://savannah.nongnu.org/cgi-bin/viewcvs/*checkout*/avr-libc/avr-libc/libm/fplib/acos.S?rev=HEAD&content-type=text/plain
It's probably better to discuss this on the avr-libc developer's
mailing list since it's actually a problem with the library, not
the compiler:
address@hidden
--
J"org Wunsch Unix support engineer
address@hidden http://www.interface-systems.de/~j/
avr-gcc-list at http://avr1.org