# [Numpy-discussion] Kronecker product

Nils Wagner nwagner at isd.uni-stuttgart.de
Thu Jul 19 02:16:42 CDT 2001

```Charles G Waldman schrieb:

> Nils Wagner writes:
>  >
>  > How can I rearrange the result of outerproduct to the result of
>  > Kronecker product with numpy ?
>  >
>
> def kron(a,b):
>     o = outerproduct(a,b)
>     o.shape = a.shape + b.shape
>     return concatenate(concatenate(o, axis=1), axis=1)

What is the difference between kron(z,eye) and kron(yt,eye) ?

Nils

-------------- next part --------------
from Numeric import *
def kron(a,b):
o = outerproduct(a,b)
o.shape = a.shape + b.shape
return concatenate(concatenate(o, axis=1), axis=1)

y = array(([5,6,7],[8,9,10]))

print 'y'
print
print y
print

z = array(([5,8],[6,9],[7,10]))

print 'z'
print
print z
print

yt = transpose(y)

print 'yt'
print
print yt
print

eye = identity(2)

a = kron(y,eye)
print
print 'kron(y,eye)'
print
print a
print

b = kron(z,eye)
print
print 'kron(z,eye)'
print
print b
print

c = kron(yt,eye)
print
print c
print
```