[metapost] Plotting a Gaussian Distribution in MetaPost

L. Nobre G. nobre at cii.fc.ul.pt
Fri Nov 9 17:30:44 CET 2007

On 08/11/2007, Kevin Liu <metapost.5.mezzopiano at spamgourmet.com> wrote:
> Hi,
> I am currently learning MetaPost, which, thanks to the great tutorials, is going
> quite well. I am mostly using it to plot graphs of functions, which has also been
> going quite well so far. However, I am experiencing significant difficulties in
> plotting a normal distribution - The only output I have been able to achieve was
> quite confusing.

Perhaps you could send your code...

You'll need an histogram of a gaussian distribution, for starters.

  for l=1 upto totalnum:
    tmp := normaldeviate;
    for k=1 upto classnum:
      if ( tmp <= k*classtep-lowrange ) and ( tmp > (k-1)*classtep-lowrange ):
	histogram[k] := incr( histogram[k] );

> The graph package handles the task quite well, but it has limitations of its own. I
> would prefer an implementation directly in MetaPost to allow for maximum
> customisation.

What customization do you need?

> Do you know of any solutions to this problem?

What exactly is the problem?

> Could this be a symptom of the very small numbers involved?


> Should I compute the numerical data and try to import it into MetaPost?


> Do you know of any bézier approximations of the gaussian distribution?

I know some pocket calculators use a sort of bézier approximations of
the gaussian distribution. About five control points are enough.

L. Nobre G. - http://burocracia.blogspot.com/
"The human species is entering a period of dramatic and potentially
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are now largely beyond our control. It is within our means, however,
to shape a positive outcome if we choose to embrace the resulting
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maturity and potential." David C. Korten in "The Great Turning"

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