On 1/8/12, andre maute <andre.maute at gmx.de> wrote:
> M:matrix([1,0,0],[v[[1,0],[0,0]],1,0],[v[[0,1],[0,0]],v[[0,1],[1,0]],1])
> (%i7) Minvinv:invert_by_lu(invert_by_lu(M))
> Maxima encountered a Lisp error:
>
> The value NIL is not of type CHARACTER.
>From what I can tell, the error is not in invert_by_lu
but somewhere downstream from GENSYM-READABLE,
which calls AFORMAT and eventually OUTPUT-TEXT*,
where it barfs. Unfortunately I can't tell what's going on
in the source code (src/mformt.lisp); too much macrology
for my tiny brain to comprehend. Oh well.
I find that
:lisp (defun gensym-readable (x) (gensym))
makes the error go away. Does that work for you?
Sorry I can't be more helpful --
Robert Dodier