[Numpy-discussion] dot product
Nadav Horesh
nadavh at visionsense.com
Tue Mar 10 06:15:38 EDT 2009
dot(X.transpose(), Y)**2 / ( (X*X).sum(0)[:,None] * (Y*Y).sum(0) )
Nadav
-----הודעה מקורית-----
מאת: numpy-discussion-bounces at scipy.org בשם Nils Wagner
נשלח: ג 10-מרץ-09 11:37
אל: numpy-discussion at scipy.org
נושא: [Numpy-discussion] dot product
Hi all,
The dot product can be defined for two vectors x and y by
x·y=|x||y| \cos(\theta),
where theta is the angle between the vectors and |x| is
the norm.
Now assume that we have arrays(matrices)
X = [x_1, ..., x_m]
Y = [y_1, ..., y_s]
m <> s
Is there a built-in function to compute the following
matrix
for i in arange(0,m):
for j in arange(0,s):
MAC[i,j] =
dot(X[:,i],Y[:,j])**2/(dot(X[:,i],X[:,i])*dot(Y[:,j],Y[:,j]))
Each element of the matrix represents the corresponding
angle squared.
Nils
_______________________________________________
Numpy-discussion mailing list
Numpy-discussion at scipy.org
http://mail.scipy.org/mailman/listinfo/numpy-discussion
-------------- next part --------------
A non-text attachment was scrubbed...
Name: winmail.dat
Type: application/ms-tnef
Size: 3075 bytes
Desc: not available
URL: <http://mail.python.org/pipermail/numpy-discussion/attachments/20090310/712378ba/attachment.bin>
More information about the NumPy-Discussion
mailing list