example: growth process of a plant

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Let

h(t) = 220 / (1 + b*exp(-a*t))

describe the growth of a plant. Let h(5) = 20.4 and h(10) = 92.9.

Find the parameters a and b.

>>> from mpmath import *
>>> h1 = lambda a, b: 220 / (1 + b*exp(-a*5)) - 20.4
>>> h2 = lambda a, b: 220 / (1 + b*exp(-a*10)) - 92.9
>>> findroot([h1, h2], (0, 1))
matrix(
[['0.393465986130316'],
 ['69.9730657971833']])

This can be verified by hand. This example could be extended to be
overdetermined.

Do you think it should replace the current example in findroot()'s
docstring (a polynomial system)?

Original issue reported on code.google.com by Vinzent.Steinberg@gmail.com on 25 Jan 2009 at 11:30

[GoogleCodeExporter]

Nice example, though the present one is fine too.

I'll write a blog entry for the 0.11 release, and I might include an example of
function interpolation to demonstrate multidimensional solving.

Original comment by fredrik....@gmail.com on 25 Jan 2009 at 12:07

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Great, looking forward!

Original comment by Vinzent.Steinberg@gmail.com on 25 Jan 2009 at 8:48

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Anything to do before closing this?

Original comment by fredrik....@gmail.com on 10 Jun 2009 at 10:49

[GoogleCodeExporter]

It was in your blog post, you can close this if you don't want it in the 
documentation.

Original comment by Vinzent.Steinberg@gmail.com on 10 Jun 2009 at 11:21

[GoogleCodeExporter]

I don't mind it in the documentation, but I don't think I'm going to add it 
myself.
So unless you are going to do it...

Original comment by fredrik....@gmail.com on 10 Jun 2009 at 11:31

[GoogleCodeExporter]

I considered it to replace the polynomial system in findroot()'s docstring, but 
you
told me it was fine...

Original comment by Vinzent.Steinberg@gmail.com on 10 Jun 2009 at 11:47

• Changed state: Fixed