Changes between Version 2 and Version 6 of Ticket #16888
- Timestamp:
- 08/28/14 13:38:05 (7 years ago)
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Ticket #16888
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David Mödinger
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u/ketzu/weak_popov_form_does_not_compute_weak_popov_form
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12755f174d1775e53ebf719612f5e984d7120677
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Ticket #16888 – Description
v2 v6 1 While working on the sage.matrix.matrix2.weak_popov_form method for performance issues I noticed something.1 While working on the sage.matrix.matrix2.weak_popov_form (for sage.matrix.matrix_misc.weak_popov_form applies the same) method for performance issues I noticed something. 2 2 3 3 The weak Popov form as defined in [MS] is not computed by this method. The other references do not call this form weak Popov form, it is a les restrictive definition for a certain row reduced form of matrix. 4 4 5 While renaming I see this as a chance to correct some (in my opinion) strange behavior of the method: 6 7 1. It takes a parameter ascend but does not relay it to the function (it is entirely ignored) 8 1. It takes a parameter ascend which is not related to either weak Popov form or row reduced form 9 1. It returns a 3-touple even though it is only expected to compute the wpf/rrf 10 1. d of the 3-touple and the sorting is unnecessary computation and should probably not be part of the method. 11 1. while N is nice to check some things, in my opinion it should only be given if asked for 12 13 Followup ticket for reimplementation of wpf: [ticket:16742 #16742.] 5 Followup ticket for reimplementation of wpf: #16742 and #16896. 14 6 15 7 [MS] T. Mulders, A. Storjohann, "On lattice reduction for polynomial[[BR]] matrices," J. Symbolic Comput. 35 (2003), no. 4, 377--401 … … 17 9 Comment of weak_popov_form: 18 10 19 OUTPUT:[[BR]] [[BR]] A 3-tuple !`(W,N,d)` consisting of:[[BR]] [[BR]] 1. !`W` - a matrix over !`k(x)` giving a weak the Popov form of self[[BR]] 2. !`N` - a matrix over !`k[x]` representing row operations used to[[BR]] transform !`self` to !`W` [[BR]] 3. !`d` - degree of respective columns of W; the degree of a column is[[BR]]the maximum of the degree of its elements11 OUTPUT:[[BR]] [[BR]] A 3-tuple !`(W,N,d)` consisting of:[[BR]] [[BR]] 1. !`W` - a matrix over !`k(x)` giving a weak the Popov form of self[[BR]] 2. !`N` - a matrix over !`k[x]` representing row operations used to[[BR]] transform !`self` to !`W` [[BR]] 3. !`d` - degree of respective columns of W; the degree of a column is[[BR]] the maximum of the degree of its elements