Re: Plotting a graph of a function f, like f(x) = e^x, with MetaPost

[Paul Menzel <paulepanter@users.sourceforge.net>]

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Dear Alan,


Am Mittwoch, den 12.10.2011, 07:36 +0200 schrieb Alan Braslau:

> Metapost can now perform calculations in double precision floating point.
> At this time, it is in the svn version and does not work yet as
> such integrated in ConTeXt (through mplib). Taco promises this for soon...

great to hear that. Just to clarify, with »now« you mean MetaPost v2, do
not you? Taco, I hope you get there without a lot of problems showing
up. If you need testers a good option would be to integrate that into
ConTeXt Standalone as an option.

> The graph package is pretty clever, and I am working on proposals on
> how to extend/rewrite this taking advantage of the new metapost
> handling of large and small numbers.

Perfect!

> To plot a function, you can create a path, as in
> path p ; p := 
> 	for i=0 upto 1000:
> 		hide (x := i/1000 ;) 
> 		if (i>0) -- fi (x,exp(x))
> 	endfor ;
> gplot p ;

What module do I need for `gplot`?

Looking at the MetaFun manual [8] I found out MetaFun even provides a
macro `function` which probably does exactly what you do above with the
for loop.

        draw function(2,"x","x**(-0.5)",1,10,1) xyscaled (2cm,2cm)
        withpen pencircle scaled 5mm withcolor
        transparent(1,.5,yellow) ;

> One proposal will be to make this even easier with new macros.

Another perfect!

One thing coming to my mind though that hopefully the wheel is not
reimplemented. I guess Gnuplot can do a lot already, but on the other
probably not as neat as Metapost when we want to color certain areas.


Thanks,

Paul


[8] http://www.pragma-ade.com/general/manuals/metafun-s.pdf

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