On Mon, Jan 5, 2015 at 1:58 PM, Nathaniel Smith <n...@pobox.com> wrote:

> I'm afraid that I really don't understand what you're trying to say. Is
> there something that you think numpy should be doing differently?
>


I liked it better when this raised an exception, instead of creating a
rectangular object array.

Josef


>
> On Mon, Jan 5, 2015 at 6:40 PM, Colin J. Williams <cjwilliam...@gmail.com>
> wrote:
>
>> One of the essential characteristics of a matrix is that it be
>> rectangular.
>>
>> This is neither spelt out or checked currently.
>>
>> The Doc description refers to a class:
>>
>>    - *class *numpy.matrix[source]
>>    
>> <http://github.com/numpy/numpy/blob/v1.9.1/numpy/matrixlib/defmatrix.py#L206>
>>
>> Returns a matrix from an array-like object, or from a string of data. A
>> matrix is a                specialized 2-D array that retains its 2-D
>> nature through operations. It has certain special operators, such as *
>> (matrix multiplication) and ** (matrix power).
>>
>> This illustrates a failure, which is reported later in the calculation:
>>
>> A2= np.matrix([[1, 2, -2], [-3, -1, 4], [4, 2 -6]])
>>
>> Here 2 - 6 is treated as an expression.
>>
>> Wikipedia offers:
>>
>> In mathematics <http://en.wikipedia.org/wiki/Mathematics>, a *matrix*
>> (plural *matrices*) is a rectangular
>> <http://en.wikipedia.org/wiki/Rectangle> *array
>> <http://en.wiktionary.org/wiki/array>*[1]
>> <http://en.wikipedia.org/wiki/Matrix_%28mathematics%29#cite_note-1> of
>> numbers <http://en.wikipedia.org/wiki/Number>, symbols
>> <http://en.wikipedia.org/wiki/Symbol_%28formal%29>, or expressions
>> <http://en.wikipedia.org/wiki/Expression_%28mathematics%29>, arranged in 
>> *rows
>> <http://en.wiktionary.org/wiki/row>* and *columns
>> <http://en.wiktionary.org/wiki/column>*.[2]
>> <http://en.wikipedia.org/wiki/Matrix_%28mathematics%29#cite_note-2>[3]
>> <http://en.wikipedia.org/wiki/Matrix_%28mathematics%29#cite_note-3> The
>> individual items in a matrix are called its *elements* or *entries*. An
>> example of a matrix with 2 rows and 3 columns is
>> [image: \begin{bmatrix}1 & 9 & -13 \\20 & 5 & -6 \end{bmatrix}.]In the
>> Numpy context, the symbols or expressions need to be evaluable.
>>
>> Colin W.
>>
>>
>>
>>
>>
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>>
>>
>
>
> --
> Nathaniel J. Smith
> Postdoctoral researcher - Informatics - University of Edinburgh
> http://vorpus.org
>
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