Re: [Visualpython-users] vector converted to numpy.ndarray

[Symion <kn...@ip...>]

Aaron Miller wrote:
> Hi VPython folks,
>
> I was attempting to run the contributed script 
> http://vpython.org/contributed/bodies.py and I get an error... I have 
> tracked it down to the fact that the dot product dot(a,b) between two 
> vectors returns a type of numpy.float64 and when I multiply this by a 
> vector I get back an array instead of a vector.
>
> A simple example that generates an error for me:
>
> from visual import *
> a=vector(1,0,0)
> b=dot(a,a)*a
> b.mag
>
> Here is the error:
> Traceback (most recent call last):
>   File "Untitled", line 4
>     b.mag
> AttributeError: 'numpy.ndarray' object has no attribute 'mag'
>
> Of course, by assigning b as vector(dot(a,a)*a) we fix this, but it 
> seems this should not be needed.  Is this a bug?
>
> Thanks,
> Aaron
> Python 2.6.2 with VPython 5.12
>
> ------------------------------------------------------
> Aaron J. Miller, Ph.D.
> Department of Physics
> 328 Palenske Hall
> Albion College, Albion, MI 49224
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>
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Try this.

from visual import *
a=vector(1,0,0)
b=vector(dot(a,a)*a)
b.mag

Symion