@Thomas Klemm -> CORDIC Article
06-02-2014, 11:42 PM
Post: #19
 Paul Dale Senior Member Posts: 1,467 Joined: Dec 2013
RE: @Thomas Klemm -> CORDIC Article
(06-02-2014 11:20 PM)pito Wrote:  Maybe it depends on how you calculate the trig functions - do you iterate Taylor against an epsilon smaller than set precision? I did it that way with decNumber (long time back though) and afaik the results were precise to the last digit.

Yes, this is what is used for SIN, COS. I will change this in the 43S, naïve Taylor series expansions aren't ideal for fixed precision results.

It won't necessarily be precise to the last digit however. Consider COS(PI/2-ULP). The Taylor series for COS(x) starts 1 - x^2/2 + ... The import thing is the leading 1. Since COS(PI/2-ULP) is very very close to zero, the Taylor expansion is subtracting almost 1 from 1 which causes quite a number of lost digits. This can be mitigated of course but you have to realise it is happening.

- Pauli
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 Messages In This Thread @Thomas Klemm -> CORDIC Article - Tugdual - 05-31-2014, 08:00 PM RE: @Thomas Klemm -> CORDIC Article - brouhaha - 06-01-2014, 02:27 AM RE: @Thomas Klemm -> CORDIC Article - Thomas Klemm - 06-01-2014, 07:32 AM RE: @Thomas Klemm -> CORDIC Article - Tugdual - 06-01-2014, 11:57 AM RE: @Thomas Klemm -> CORDIC Article - Paul Dale - 06-01-2014, 12:12 PM RE: @Thomas Klemm -> CORDIC Article - Thomas Klemm - 06-01-2014, 07:32 PM RE: @Thomas Klemm -> CORDIC Article - Claudio L. - 06-04-2014, 04:31 PM RE: @Thomas Klemm -> CORDIC Article - Tugdual - 06-01-2014, 07:48 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-01-2014, 08:28 PM RE: @Thomas Klemm -> CORDIC Article - Marcus von Cube - 06-02-2014, 08:47 PM RE: @Thomas Klemm -> CORDIC Article - Thomas Klemm - 06-02-2014, 06:39 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-02-2014, 10:13 PM RE: @Thomas Klemm -> CORDIC Article - Paul Dale - 06-02-2014, 10:26 PM RE: @Thomas Klemm -> CORDIC Article - Tugdual - 06-02-2014, 10:53 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-02-2014, 10:58 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-02-2014, 11:05 PM RE: @Thomas Klemm -> CORDIC Article - Paul Dale - 06-02-2014, 11:08 PM RE: @Thomas Klemm -> CORDIC Article - Tugdual - 06-02-2014, 11:13 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-02-2014, 11:20 PM RE: @Thomas Klemm -> CORDIC Article - Paul Dale - 06-02-2014 11:42 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-03-2014, 02:02 PM RE: @Thomas Klemm -> CORDIC Article - Claudio L. - 06-04-2014, 05:57 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 02:52 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 06:06 PM RE: @Thomas Klemm -> CORDIC Article - Claudio L. - 06-04-2014, 06:21 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 06:30 PM RE: @Thomas Klemm -> CORDIC Article - Claudio L. - 06-04-2014, 06:37 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 06:45 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 07:16 PM RE: @Thomas Klemm -> CORDIC Article - Claudio L. - 06-04-2014, 07:36 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 07:30 PM RE: @Thomas Klemm -> CORDIC Article - Claudio L. - 06-04-2014, 07:41 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 07:51 PM RE: @Thomas Klemm -> CORDIC Article - Claudio L. - 06-04-2014, 09:05 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 08:12 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 08:34 PM RE: @Thomas Klemm -> CORDIC Article - Claudio L. - 06-04-2014, 09:21 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 09:21 PM RE: @Thomas Klemm -> CORDIC Article - Claudio L. - 06-04-2014, 09:39 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 09:33 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 09:41 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 09:50 PM RE: @Thomas Klemm -> CORDIC Article - pito - 06-04-2014, 10:46 PM

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