Hi,
On May 30, 2:34 pm, gpap <[email protected]> wrote:
> > Hi,
>
> > I am very new to python and I am currently trying to migrate some code
> > from mathematica. What I'm stuck with is the following:
>
> > I have created a linear system A.x = B, and I have a list of
> > replacement rules I would like to apply to the matrix A and the array
> > B before I go on to solve it. A minimal working example is as follows:
>
> > #####################
>
> > from numpy import *
> > from sympy import *
> > t, t1, t2, t3 = symbols ('t', 't1', 't2', 't3')
> > A = array( [ [sin(t1)], [0], [sin(t3)], [sin(t)] ] )
> > B = array( [sin(t1), 0, sin(t3), sin(t)] )
> > def Rule_Sub(x): return (x).subs(Repl_Rules)
> > B= map(Rule_Sub, B)
> > for i in range(len(A))
>
> > #####################
> > Now, I'd like to be able to do the same to the matrix A, i.e. apply a
> > list of replacement rules
>
> contd (I somehow managed to hit send before finishing). basically I
> was looking for a neat way of applying my replacement rules to the 2x2
> array
> i.e. something along the lines of
>
> map(Rule_Sub, map(Rule_Sub, A))
>
> and also a clever way I could not bounce with an error on the zeros of
> my otherwise symbolic matrix when applying the replacement rules
> i.e. now when map(Rule_Sub, B) hits the zero it gives error since 0 is
> an integer - is there a way for sympy to pass it on as a symbol with
> value 0?
I'm not sure what you want to do, but would something along these
lines work for you?
"""
from sympy import *
t, t1, t2, t3 = symbols('t t1 t2 t3')
A = Matrix([sin(t1), 0, sin(t3), sin(t)])
B = A.T
repl_rules = {t1: t, t3: 0}
print A.subs(repl_rules)
print
print B
"""
Vinzent
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