[metapost] re: MetaPost 0.891 announcement
laurent at math.toronto.edu
Tue Mar 22 03:28:04 CET 2005
Your answers are helpful, but there are still a few
patches of fog in my view.
> 5. The EPS output no longer contains spaces
> within PostScript strings
Which processors were troubled by spaces in
those PostScript strings; and why?
> 6. The turningnumber was sometimes wrong in unexpected ways. The new
> implementation is still sometimes wrong (when there are strange path
> segments involved), but in a much more predictable way: the new code
> always draws straight lines between the knot points, and calculates
> the turningnumber based on that path instead of the actual path. The
> effect is that cusps and loops within segments are now completely
> ignored. A more thorough fix of turningnumber is planned for the
> next release.
[[ Knotty remark: Knuth does not use the term "knot point" in mfbook
(?!). But one can talk of the "integral points" or "integral time
points" of a path and be understood by all users of mp and mf.]]
I am not keen on introducing systematic functionality in any public
mp version that is ab initio known to be inappropriate and impermanent.
A more orthodox alternative is to introduce the new primitive
for what you proposed for the interim "turningnumber"
and maintain it forever as a useful sanity check on the 'optimum'
turningnumber that has not yet been decided and debugged.
I have railed often against ignoring the inevitable instabilities
of turningnumber. They should be signaled somehow. But how?
Example: Consider the mirror image 'almost perfect' circles
With your current proposal, what does mp say about their respective
turningnumber's (ie secantturningnumber's).
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