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Cannot convert int to sage.rings.integer.Integer

asked 2011-05-02 07:23:12 -0500

paragon gravatar image

I created a minimal example in the file bad.py

from sage.all import *

j = 0
m = matrix(3,3)
m.insert_row(j, [1,1,1])

Then from sage:

sage: load bad.py
TypeError: Cannot convert int to sage.rings.integer.Integer

I think I can see an easy workaround, I can wrap all the 1's in Integer() (or change the name of the file to .sage so the preparser does it), but why is that necessary? Is this a bug? Why would sage not be able to convert int to Integer? Isn't that a pretty obvious conversion?

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It's important to have a way of using Python types like int without having the preparser rewrite them, that's why the load and attach behavior of `.py` files and `.sage` files is different. But, I agree, it should be trivial for the matrix code to coerce `int` to `Integer`. It could be that the coercion is not done for a specific reason. I'm also curious why if you declare `m = matrix(QQ, 3, 3)` that `m` no longer has an `insert_row` method.

benjaminfjones gravatar imagebenjaminfjones ( 2011-05-02 08:00:29 -0500 )edit

Yeah, insert_row seems to only be defined for dense integer matrices - check out sage: search_def('insert_row'). Presumably at least some of this could be recycled. Sounds like another Trac ticket to file! Or search for.

kcrisman gravatar imagekcrisman ( 2011-05-02 08:50:51 -0500 )edit

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answered 2011-05-02 09:01:15 -0500

kcrisman gravatar image

I think the problem might be that

cdef Integer z

is part of the code here, and then there is no coercion to the integers, it's just assumed that it is one. Trying

    z = Integer(row[k])

seems to fix it, though this is probably inelegant and inefficient.

Here is a minimal example inside Sage itself, for reference.

sage: m = matrix([[int(1),int(1)],[int(1),int(1)]])
sage: m.insert_row(1,[int(1),int(1)])
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
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This is now #11328.

kcrisman gravatar imagekcrisman ( 2011-05-11 07:19:18 -0500 )edit

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Asked: 2011-05-02 07:23:12 -0500

Seen: 936 times

Last updated: May 02 '11