Re: [NTG-context] Implicit plots/level curves possible?

8 Oct 2018


      On Mon, 8 Oct 2018, Alan Braslau wrote:
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On Mon, 8 Oct 2018 16:00:10 -0400 (EDT)
Aditya Mahajan  wrote:
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On Sun, 7 Oct 2018, Hans Hagen wrote:
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On 10/7/2018 7:14 PM, Alan Braslau wrote:
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On Sun, 7 Oct 2018 17:25:35 +0200
"Mikael P. Sundqvist"  wrote:
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ContourPlot[2 x^5 + x y + y^5 == 0, {x, 0, 2}, {y, -2, 1/2}]
Brut force:
[...]
as this takes some time here's a cheat:
\starttext
\startbuffer[demo]
[...]
\stopbuffer
\startTEXpage
    \typesetbuffer[demo]
\stopTEXpage
\stoptext
a next run the already prepared buffer will be taken unles it has been
changed.
I thought that this will also be a good usecase of showing Lua+MP
interaction. I wrote the code below following the metafun manual, but I cannot
get it to compile. What am I missing?
You need to put it into the mp namespace:
Thanks. The metafun manual is confusing in this regard and I got 
the impression that any lua namespace could be used.
...
(then eps should be made a linear function of xi)
Oh, I missed that. Thanks.
...
(and, indeed this is much faster than calculating in MP)
Yes. Iterating over 10^6 values on a 1GHz computer should roughly take 
1ms in any reasonable programming language. Metapost for loops work with 
macro expansion, which can be very expensive for large loops.

Aditya