# [Numpy-discussion] objects are not aligned. Matrix and Array

Wayne Watson sierra_mtnview@sbcglobal....
Sat Dec 19 00:20:21 CST 2009

```Is math automatic (built-in)?

Same result with np.dot(m2, m1).

Ah, this works. dotres = np.dot(m2.T, m1).
It looks to me like the shapes are the same, so maybe dot() requires one
as a column vector and one as a row.

Thanks.

Charles R Harris wrote:
>
>
> On Fri, Dec 18, 2009 at 10:20 PM, Wayne Watson
> <sierra_mtnview@sbcglobal.net <mailto:sierra_mtnview@sbcglobal.net>>
> wrote:
>
>     This program gives me the message following it:
>     ================Program==========
>     import numpy as np
>     from numpy import matrix
>     import math
>
>
> You don't want math.
>
>
>     def sinD(D): # given in degrees, convert to radians
>     def cosD(D):
>
>
> def sinD(D):
>
>
>     r = math.sqrt(2*2+5*5)
>
>
> np.hypot(2, 5)
>
>
>     print r
>     m1 = matrix([[2], [5]])
>     print "m1: ", m1
>
>     theta = 5.0 # degrees
>     #CW 2x2 clockwise matrix
>     rotCW = matrix([ [cosD(theta), sinD(theta)], [-sinD(theta),
>     cosD(theta)] ])
>
>     print rotCW
>
>     m2 = rotCW*m1
>     print "m2: ", m2
>     print "aaaaaaaa: ", type(m1), type(m2)
>     m1=np.array(m1)
>     m2=np.array(m2)
>
>     print "zzzzzzzz: ", type(m1), type(m2)
>
>     print"dot, ..."
>     dotres = np.dot(m1,m2)
>
>
> Try np.dot(m2, m1), m1 is a column matrix.
>
>
>     print "dotres", dotres
>     ==============end==========
>
>     ==========Output msgs========
>     5.38516480713
>     m1:  [[2]
>      [5]]
>     [[ 0.9961947   0.08715574]
>      [-0.08715574  0.9961947 ]]
>     m2:  [[ 2.42816811]
>      [ 4.806662  ]]
>     aaaaaaaa:  <class 'numpy.core.defmatrix.matrix'> <class
>     'numpy.core.defmatrix.matrix'>
>     zzzzzzzz:  <type 'numpy.ndarray'> <type 'numpy.ndarray'>
>     dot, ...
>
>     Traceback (most recent call last):
>      File
>     line 30, in <module>
>        dotres = np.dot(m1,m2)
>     ValueError: objects are not aligned
>     ================end msgs===========
>     Why the msg? The types look alike and each array/matrix contains two
>     elements..
>
>
> Chuck
>
> ------------------------------------------------------------------------
>
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>

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