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 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 return math.sin(math.radians(D)) def cosD(D): return math.cos(math.radians(D))

def sinD(D): return np.sin(np.deg2rad(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: zzzzzzzz: dot, ...

Traceback (most recent call last): File "C:/Sponsor_Meteors/Sentinel_Development/Development_Sentuser+Utilities/Playground/junk.py", 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

------------------------------------------------------------------------

_______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion

-- Wayne Watson (Watson Adventures, Prop., Nevada City, CA) (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time) Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet "... humans'innate skills with numbers isn't much better than that of rats and dolphins." -- Stanislas Dehaene, neurosurgeon Web Page:

On Sat, Dec 19, 2009 at 4:53 AM, Chris Colbert wrote:

On Sat, Dec 19, 2009 at 6:43 AM, Charles R Harris < charlesr.harris@gmail.com> wrote:

...

On Fri, Dec 18, 2009 at 10:20 PM, Wayne Watson < 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.

Why do you say that? The builtins are MUCH faster than numpy for single values:

In [1]: import math

In [2]: import numpy as np

In [3]: %timeit np.sin(1.57) 100000 loops, best of 3: 2.41 us per loop

In [4]: %timeit math.sin(1.57) 10000000 loops, best of 3: 165 ns per loop

In [6]: %timeit np.array([np.sin(1.57)]) 100000 loops, best of 3: 11.5 us per loop

In [7]: %timeit np.array([math.sin(1.57)]) 100000 loops, best of 3: 7.01 us per loop

Fair point. I was thinking of the vector case down the road. Chuck