#3447 eigenvalues called on array causes Maxima to crash

[Tom Dean]

An incorrect call to eigenvalues() causes maxima to display an error message and exit. If maxima is started with 'xterm -e maxima' it sometimes causes the xterm to close.

Console output:

> /usr/local/bin/maxima
Maxima branch_5_41_base_450_g0b7d9cd_dirty http://maxima.sourceforge.net
using Lisp GNU Common Lisp (GCL) GCL 2.6.12
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) A: make_array(any,3,3);
(%o1) {Lisp Array: #2A((NIL NIL NIL) (NIL NIL NIL) (NIL NIL NIL))}
(%i2) fill_array(A,[x-y, x, 0, x, x-y, x, 0, x, x-y]);
(%o2) fill_array({Lisp Array: #2A((NIL NIL NIL) (NIL NIL NIL) (NIL NIL NIL))}, 
[x - y, x, 0, x, x - y, x, 0, x, x - y])
(%i3) listarray(A);
(%o3) [false, false, false, false, false, false, false, false, false]
(%i4) eigenvalues(A);

Maxima encountered a Lisp error:

 Condition in MACSYMA-TOP-LEVEL [or a callee]: INTERNAL-SIMPLE-ERROR: Caught fatal error [memory may be damaged]

Automatically continuing.
To enable the Lisp debugger set *debugger-hook* to nil.
(%i5) eigenvalues(A);

Unrecoverable error: Segmentation violation..

[Robert Dodier]

I see the error is caused by calling eigenvalues on an array, while eigenvalues (and most other functions) expect a matrix, which is a different kind of object in Maxima.

Tom, I think what you want is:

A : matrix ([x - y, x, 0], [x, x - y, x], [0, x, x - y]);
eigenvalues (A);

[Robert Dodier]

The error here is that eigenvalues and other functions which expect a matrix should print a more intelligible error message if they get some other kind of input.