On 2009-06-06 00:34, Ajith Kumar wrote:
Hello,
I ran the following code (Using Debian 5.0)
from numpy import *
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a = arange(1.,10.)
b = reshape(a, [3,3])
c = linalg.inv(b)
print b
print c
print dot(b,c)
print dot(c,b)
And the result is
[[ 1. 2. 3.]
[ 4. 5. 6.]
[ 7. 8. 9.]]
[[ 3.15221191e+15 -6.30442381e+15 3.15221191e+15]
[ -6.30442381e+15 1.26088476e+16 -6.30442381e+15]
[ 3.15221191e+15 -6.30442381e+15 3.15221191e+15]]
[[-0.5 -1. -1. ]
[-1. -2. 2. ]
[-1.5 -3. 1. ]]
[[ 5.5 8. 10.5]
[ 3. 0. -3. ]
[ -1. 0. -3. ]]
NOT the identity matrix. Any help ?
You have a very singular matrix (2*a[1] - a[0] == a[2]). You cannot invert it
numerically and expect sensible results.
--
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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