# [SciPy-dev] Numpy example for arctan2 perhaps wrong/misleading/confusing?

David Huard david.huard@gmail....
Mon Jun 9 13:08:27 CDT 2008

```2008/6/9 Samuel John <scipy@samueljohn.de>:

> Hi!
>
> > What you want is this :
> >
> >> [4]: def arctan2(vectors):
> >    ...:     """Return the angle between the x axis and each vector in
> > vectors."""
> >    ...:     v = np.atleast_2d(vectors)
> >    ...:     return np.arctan2(v[:,0], v[:,1])
> >    ...:
> >
> >> [5]: arctan2(([0,0], [1,0]))
> > < [5]: array([ 0.        ,  1.57079633])
>
> Indeed, very nice.
>
>
> > You could also use the numpy.angle function which returns the angle of a
> > complex argument.
> >
> >> [15]: np.angle([0, 1j])
> >  <[15]: array([ 0.        ,  1.57079633])
>
> Cool, I was not aware of this function. Perfect.
> Unfortunately there is no docstring *g*...
>

What version of Numpy are you using ? Here is what I have:

Return the angle of the complex argument z.

Examples
--------
0.78539816339744828
>>> numpy.angle(1+1j,deg=True) # in degrees
45.0

>
>
> --
>  Samuel
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>
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