Matrix row_del and row_insert operation with out of bound index

[Gaurav Dhingra]

Hi all

>>> from sympy import *

>>> M = Matrix( [ [1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6] ] )

>>> M.row_del ( 8 )                                            # any index >= M.rows to be used

>>> print( M )

Matrix( [ [ 1, 2, 3], [2, 3, 4], [3, 4, 5] ] )               # deletes the last row of Matrix for Index >= M.rows

>>> N = Matrix( [ [ 1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6] ] )

>>> N.row_del( -10 )

>>> print( N )                                                     # deletes the last row of Matrix with any `Negative Index`

Matrix( [ [ 1, 2, 3], [2, 3, 4], [3, 4, 5] ] )

But the output for .row_insert() shows different behavior

>>> M = Matrix( [ [1, 2, 3], [2, 3, 4], [3, 4, 5] ] )

>>> M.row_insert ( 10, Matrix( [ [ 5, 5, 5 ] ] ) )

Matrix( [ [1, 2, 3], [2, 3, 4], [3, 4, 5], [5, 5, 5] ] )   # inserts the row at the very end for Index >= M.rows

>>> N = Matrix( [ [ 1, 2, 3], [2, 3, 4], [3, 4, 5] ] )

>>> N.row_insert( -10, Matrix( [ [5, 5, 5 ] ] ) )

Matrix( [ [5, 5, 5], [1, 2, 3], [2, 3, 4], [3, 4, 5] ] )     # inserts the row at the very beginning for `Negative Index`

First of all i  expected that an IndexError be raised in all cases. Because i think it should follow something like  a = [1, 2, 3] and del a[ 10 ] which raises an error. 

But even if not error then it should be more consistent with the indices. Is it the way the things are expected to work ?

[Chris Smith]

The question is how you would append a row using the insert method if you disallowed indices that are out of range. I agree that the negative indice behavior is wrong for deletion: it should have deleted the first row as you indicate.

[Gaurav Dhingra]

I agree with your statement that: "These all operations be allowed". For the M.row_del( ) for negative indices, should I Open an Issue and Fix it ?