About LU factorization

[salvomic]

(06-04-2015 04:57 PM)Werner Wrote:  ...
Crout factorisation alternatingly computes a row and a column...
Cheers, Werner

hi Werner,
both methods have goods and issues...
Maybe Parisse and Tim could tell us more about the Prime and LU...

However for matrices operations perhaps it could be better to have also some little commands or helps, like a command to extract pivots, to get cofactors, adjoint, minors, and also factorizations LDU (LDV) and LDLt. As they are missing, I'm trying to make some programs, but for pivots I'm getting these troubles...
Some other calculators have those commands, if I well remember (i.e., TI 89/Voyage had adj / cofactor function)...
For example I use a lot a little program to get minor of a matrix:

Code:



#cas 
matrixminor(m,r,c):=
BEGIN
  m:= delrows(m,r);
  m:= delcols(m,c);
END;
#end

Simple but useful, it helps to don't use delrows() and delcols() more and more. It's alternative to the subMat() command (syntax: subMat(m, r1, c1, r2,c2), and perhaps more short

I made a program to calculate Cofactor matrix and adjoint matrix (see here)...

Salvo