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Re: How to get X/Y-extent of a bezier-curve?
From: |
David Kastrup |
Subject: |
Re: How to get X/Y-extent of a bezier-curve? |
Date: |
Wed, 07 Oct 2015 14:16:08 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) |
Thomas Morley <address@hidden> writes:
> 2015-10-07 13:13 GMT+02:00 David Kastrup <address@hidden>:
>
>> If you take a look at the following, it is quite inefficient since it
>> repeats a lot of calculations instead of assigning partial results to
>> let-bound variables. It also uses the straight PQ formula whereas the
>> usual way to avoid numerical inaccuracies is to use the PQ formula only
>> for the zero where the sign of the +/- does not lead to cancellation and
>> get the other zero via Viata's rule.
>>
>> (define (bezier-part-min-max x1 x2 x3 x4)
> [...]
>
> No promise, but maybe I'll take a look.
> Not that I know about Viata's or L'hopital's rule, but google maybe
> helpfull, otherwise I'll reask
Uh, it's Vieta's rule, sorry for the typo. L'hopital is a rule for the
limit of fractions (basically, when f/g -> 0/0 you might get the
limiting value by looking at the limit of the quotient of derivatives
f'/g' instead). No idea how it would apply here.
--
David Kastrup
- How to get X/Y-extent of a bezier-curve?, Thomas Morley, 2015/10/08
- Re: How to get X/Y-extent of a bezier-curve?, David Kastrup, 2015/10/08
- Re: How to get X/Y-extent of a bezier-curve?, Thomas Morley, 2015/10/08
- Re: How to get X/Y-extent of a bezier-curve?, David Kastrup, 2015/10/08
- Re: How to get X/Y-extent of a bezier-curve?, Thomas Morley, 2015/10/08
- Re: How to get X/Y-extent of a bezier-curve?,
David Kastrup <=
- Re: How to get X/Y-extent of a bezier-curve?, Thomas Morley, 2015/10/08
- Re: How to get X/Y-extent of a bezier-curve?, Ed Gordijn, 2015/10/09
- Re: How to get X/Y-extent of a bezier-curve?, David Kastrup, 2015/10/09
- Re: How to get X/Y-extent of a bezier-curve?, Thomas Morley, 2015/10/09
- Re: How to get X/Y-extent of a bezier-curve?, David Kastrup, 2015/10/09
- Re: How to get X/Y-extent of a bezier-curve?, BB, 2015/10/08
- Re: How to get X/Y-extent of a bezier-curve?, Thomas Morley, 2015/10/08
- Re: How to get X/Y-extent of a bezier-curve?, BB, 2015/10/08