[sage-devel] Re: Kernel and Null Space Bases

2009-01-29 Thread Rob Beezer
I've added this into Trac. http://trac.sagemath.org/sage_trac/ticket/5135 Jason - thanks for the heads-up on 3058. William - someplace you *have* to turn rows into columns. ;-) In my book, I think it is all buried into "column space of A = row space of transpose(A)" or something similar. Wou

[sage-devel] Re: Kernel and Null Space Bases

2009-01-29 Thread Rob Beezer
I've added this into Trac. http://trac.sagemath.org/sage_trac/ticket/5135 Jason - thanks for the heads-up on 3058. William - someplace you *have* to turn rows into columns. ;-) In my book, I think it is all buried into "column space of A = row space of transpose(A)" or something similar. Wou

[sage-devel] Re: Kernel and Null Space Bases

2009-01-28 Thread Jason Grout
Rob Beezer wrote: > William, >> >> I think the right change for your application would be to change this >> line in left_kernel: >> >> W = V.submodule(basis) >> >> to >> >> if echelonize: >> W = V.submodule(basis) >> else: >> W = V.submodule_with_basis(basis) >> >

[sage-devel] Re: Kernel and Null Space Bases

2009-01-28 Thread William Stein
On Wed, Jan 28, 2009 at 3:55 PM, Rob Beezer wrote: > > William, > > Thanks for the reply. I hadn't dug deep enough to find the > "with_basis" variant of the submodule constructor, so I like the > suggested approach. Barring anymore significant conversation here, > I'll take on submitting this w

[sage-devel] Re: Kernel and Null Space Bases

2009-01-28 Thread Rob Beezer
William, Thanks for the reply. I hadn't dug deep enough to find the "with_basis" variant of the submodule constructor, so I like the suggested approach. Barring anymore significant conversation here, I'll take on submitting this with a ticket and a patch. It'll be a learning experience for me

[sage-devel] Re: Kernel and Null Space Bases

2009-01-28 Thread William Stein
On Wed, Jan 28, 2009 at 3:07 PM, Rob Beezer wrote: > > A question about computing bases for kernels or null spaces of > matrices. > > When working with students studying linear algebra for the first time, > I like to construct basis vectors for the (right) kernel by working > through the indices