eigenvalues, part: fell off the end

>>>>> "Barton" == Barton Willis <willisb at unk.edu> writes:

    Barton> (%i7) nullspace(matrix([0,0],[0,0])), ratmx : true;
    Barton> Maxima encountered a Lisp error:
    Barton> GREAT: internal error: unexpected MRAT argument
    Barton> Automatically continuing.
    Barton> To enable the Lisp debugger set *debugger-hook* to nil.
    Barton> (%i8) build_info();
    Barton> (%o8) build_info(version="5.30.0",timestamp="2013-06-01 21:29:43",host="i686-pc-mingw32",lisp_name="GNU Common Lisp (GCL)",lisp_version="GCL 2.6.8")'

    Barton> Maybe I've forgotten something about using the backtrace with GCL?

    Barton> (%i2) :lisp( setf *debugger-hook* nil)
    Barton> NIL
    Barton> (%i2) :lisp(setf use-fast-links nil)
    Barton> NIL
    Barton> (%i2) nullspace(matrix([0,0],[0,0])), ratmx : true;
    Barton> GREAT: internal error: unexpected MRAT argument
    Barton> Fast links are on: do (use-fast-links nil) for debugging
    Barton> Broken at PROGN.  Type :H for Help.
    Barton> 1 (Continue) Maxima top-level
    Barton> 2 (Abort) Return to top level.
    Barton> dbl:MAXIMA>> :bt
    Barton> #0   RUN {} [ihs=4]
    Barton> NIL
    Barton> dbl:MAXIMA>> 

I can reproduce this issue (using current sources and cmucl).

The error message (and partial backtrace) is:

Error in function GREAT:  GREAT: internal error: unexpected MRAT argument
   [Condition of type SIMPLE-ERROR]

Restarts:
  0: [MACSYMA-QUIT] Maxima top-level
  1: [ABORT       ] Skip remaining initializations.

Debug  (type H for help)

(GREAT ((MRAT SIMP NIL NIL) 1 . 1) ((MRAT SIMP NIL NIL) 0 . 1))
Source: 
; File: /usr/local/google/home/rtoy/src/sourceforge/maxima/src/simp.lisp
(ERROR "GREAT: internal error: unexpected MRAT argument")
0] back

0: (GREAT ((MRAT SIMP NIL NIL) 1 . 1) ((MRAT SIMP NIL NIL) 0 . 1))
1: (B-SEARCH-EXPR
    (($MATRIX SIMP) ((MLIST SIMP) ((MRAT SIMP NIL NIL) 0 . 1))
     ((MLIST SIMP) ((MRAT SIMP NIL NIL) 1 . 1)))
    ((($MATRIX SIMP) ((MLIST SIMP) ((MRAT SIMP NIL NIL) 1 . 1))
      ((MLIST SIMP) ((MRAT SIMP NIL NIL) 0 . 1))))
    0
    1)
2: ($ADJOIN
    (($MATRIX SIMP) ((MLIST SIMP) ((MRAT SIMP NIL NIL) 0 . 1))
     ((MLIST SIMP) ((MRAT SIMP NIL NIL) 1 . 1)))
    (($SET SIMP)
     (($MATRIX SIMP) ((MLIST SIMP) ((MRAT SIMP NIL NIL) 1 . 1))
      ((MLIST SIMP) ((MRAT SIMP NIL NIL) 0 . 1)))))