# [Numpy-tickets] [NumPy] #524: Scalar arithmetic with arrays produces values that masquerade as a particular type but are not

NumPy numpy-tickets@scipy....
Mon May 21 17:17:23 CDT 2007

```#524: Scalar arithmetic with arrays produces values that masquerade as a
particular type but are not
--------------------+-------------------------------------------------------
Reporter:  socha   |       Owner:  somebody
Type:  defect  |      Status:  new
Priority:  normal  |   Milestone:
Component:  Other   |     Version:  1.0.2
Severity:  normal  |    Keywords:
--------------------+-------------------------------------------------------
Multiplication and addition of scalars with arrays produces values that
say they are of a particular type but are not actually of that type.

Here's an example:
{{{
Microsoft Windows XP [Version 5.1.2600]

C:\Documents and Settings\socha>python
Python 2.4.3 - Enthought Edition 1.0.0 (#69, Aug  2 2006, 12:09:59) [MSC
v.1310 32 bit (Intel)] on win32
>>> import numpy
>>> numpy.__version__
'1.0.2'
>>> from numpy import array
>>> a = array([1000])
>>> b = 1000*array([1])
>>> type(a[0]) == type(b[0])
False
>>> type(a[0])
<type 'numpy.int32'>
>>> type(b[0])
<type 'numpy.int32'>
>>> from numpy import int32
>>> type(a[0]) == int32
True
>>> type(b[0]) == int32
False
>>> b = array([1000])
>>> type(b[0]) == int32
True
>>> type(a[0]) == type(b[0])
True
>>> c = 1000+array([1])          # also happens for '+'
>>> c
array([1001])
>>> type(c[0]) == int32
False
>>>
}}}

Daniel Terhorst and David Socha ([http://www.urbansim.org UrbanSim])

--
Ticket URL: <http://www.projects.scipy.org/scipy/numpy/ticket/524>
NumPy <http://projects.scipy.org/scipy/numpy>
The fundamental package needed for scientific computing with Python.
```