Difference of cultures? Re: Matrix manipulations Re: [Maxima] Size of a matrix

Excuse me, but I was taught at my University that for a matrix M its 
submatrix contains rows i1,i2,... and columnt j1,j2,.... And a minor of 
k-th order of a matrix is a determinant of a submatrix od size k... my 
Encyclopedia of Mathematics say so too. So, when I look for a certain 
function in the docs I assume it is named corectly.
--
Andrei Zorine

p.s. thanks for genmatrix trick.

Stavros Macrakis wrote:
>>Maxima lacks some useful functions that operate on matrices. 
>>Another two of them are _deleting_ rows and columns.
>>...Does this mean that a) maxima users never delete rows/cols,
>>they only add cols/rows, or b) these functions are 
>>present but are undocumented, or c) writing these functions 
>>should be a primer finger-excersise for any maxima beginner?
> 
> 
> The functions are present and documented.
> 
>  - Function: SUBMATRIX (m1, ..., M, n1, ...)
>      creates a new matrix composed of the matrix M with rows mi
>      deleted, and columns ni deleted.
> 
>  - Function: MINOR (M, i, j)
>      computes the i,j minor of the matrix M.  That is, M with row i and
>      column j removed.
> 
> They are also easy finger exercises for beginners (no error-checking for
> simplicity):
> 
> removerow(m,r):=
>   genmatrix(
>      lambda([i,j],
>         m[ if i>=r then i+1 else i, j ]),
>      length(m)-1,
>      length(m[1]));
> 
> removecol(m,c):=
>   genmatrix(
>      lambda([i,j],
>         m[ i, if j>=c then j+1 else j ]),
>      length(m),
>      length(m[1])-1);           
> 
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>