Simultaneous Matrix Equations



On Thu, 2006-03-09 at 20:56 +0100, laurent couraud wrote:

> > It is possible to extract the matrix elements and construct
> > the equations by writing a little program; maybe there is
> > a command to do this.
> > 
> 
> COEFMATRIX ([eq1, ...], [var1, ...]) 

coefmatrix does the opposite of what was needed.

"Extract the matrix elements and construct the equations"
in this case meant going from:
   eqn: matrix([x],[y]) = matrix([1],[2]);
to:
   [x=1, y=2]

which can be done with:
   makelist(lhs(eq)[i][1] = rhs(eq)[i][1], i, 1, length(lhs(eq)));

By the way, I just noticed the documentation of coefmatrix is wrong:

 -- Function: coefmatrix ([<eqn_1>, ..., <eqn_m>], [<x_1>, ..., <x_n>])
     Returns the coefficient matrix for the variables <eqn_1>, ...,
     <eqn_m> of the system of linear equations <x_1>, ..., <x_n>.

Does any developer have any objection if I change it to:

 -- Function: coefmatrix ([<eqn_1>, ..., <eqn_m>], [<x_1>, ..., <x_n>])
     Returns the coefficient matrix for the variables <x_1>, ...,
     <x_n> of the system of linear equations <eqn_1>, ..., <eqn_m>.
?

I guess for simple changes like this I just commit a a new version of
doc/info/Matrices.texi; is that enough, or should I do something else?

Jaime