Thank you so much for the prompt and helpful reply Dmitrii! Much 
appreciated. 

Best,
Boyan

On Saturday, October 19, 2019 at 4:53:32 AM UTC-4, [email protected] wrote:
>
> On Fri, Oct 18, 2019 at 09:09:01PM -0700, Boyan Kostadinov wrote: 
> > I want to get the transformation matrix from the echelon form reduction 
> > over finite fields but I found in the SageMath documentation the 
> following 
> > statement: 
> > 
> > *The matrix library used for Z/pZ/p-matrices does not return the 
> > transformation matrix, so the transformation option is ignored* 
> > 
> > Link: 
> > 
> http://doc.sagemath.org/html/en/reference/matrices/sage/matrix/matrix2.html#sage.matrix.matrix2.Matrix.echelon_form
>  
> >   
> > 
> > More specifically, the call:  *M.echelon_form(transformation=True**) 
> *does 
> > not return the transformation matrix T when M is over a finite field, 
> only 
> > the echelon matrix E; T is such that we have T*M=E, so T is just the 
> > product of the elementary matrices, which perform the reducing row 
> > operations. 
> > 
> > Is there any workaround to get the transformation matrix T over a finite 
> > field? Can I get the transformation matrix T over ZZ and then reduce it 
> > over the finite field? 
>
> Yes, this should work (with a loss in efficiency, which can be 
> substantial on large matrices). Anyway, this is how to do this. 
>
> sage: MS = MatrixSpace(GF(19),2,3) 
> ....: C = MS.matrix([1,2,3,4,5,6]) 
> ....: E,T = map(lambda t: matrix(GF(19),t), 
> matrix(ZZ,C).echelon_form(transformation=True)) 
> ....: T*C == E 
> ....: E in MS 
> ....: 
> True 
> True 
>
> --------------------------------------------------------------- 
>
> HTH 
> Dmitrii 
> > 
> > Any advice would be much appreciated. 
> > 
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>  
>
>
>

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