[SciPy-user] What can and cannot be interpreted as a vector by odeint?
Robert Kern
robert.kern at gmail.com
Fri Nov 17 01:41:00 CST 2006
David Goldsmith wrote:
> I was having trouble getting odeint to work w/ what I thought should be
> legitimate vector arguments. Looking for examples, I found
> test_integrate.py and thus found at least one way which works. However,
> I'm left wondering why the following behaves the way it does:
>
> >>> import numpy as N
> >>> import scipy as S
> >>> from scipy import integrate as SI
> >>> def f(y,t0=0):
> ... return N.matrix([[0,1],[-1,0]])*N.matrix([[y[0]],[y[1]]]) #
> [y,y']'=f([y,y']) = "simplest" harmonic oscillator system
You'll probably want to return a real array object, not a matrix. The
handwritten C code that wraps FORTRAN ODEPACK was written long before arrays
could be subclassed.
> PS: Is there a substantive difference between odeint and odepack (I
> couldn't detect one from their resp. help doc)?
odeint() is a function that wraps the functionality of ODEPACK. It is defined in
the module called odepack.
--
Robert Kern
"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco
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