upgrade degree-1 matrices to degree 2 when doing a comparison

[Alex-Jordan]

This is to address an issue I raised in the thread for #1215.

[pstaabp]

I think it would be a good idea to add these cases to the test suite.

[drgrice1]

Could you provide a PG example of this? You gave an example mathematically in #1215 (comment), but I am having a hard time producing this in an actual PG problem. For example, I tried the following

DOCUMENT();

loadMacros('PGstandard.pl', 'PGML.pl', 'PGcourse.pl');

$vector = Vector(1, 0, 0);

$matrix = Matrix([ [ 1, 0, 0 ], [ 0, 1, 0 ], [ 0, 0, 1 ] ]);

$result = $matrix * $vector;

$result2 = Matrix([ [ 1, 0, 0 ] ]);

BEGIN_PGML
[`[$vector]`] is a [@ ref($vector) @]

[`[$matrix]`] is a [@ ref($matrix) @]

[`[$result]`] is a [@ ref($result) @]

[`[$result2]`] is a [@ ref($result2) @]

[`[$matrix] \cdot [$vector] = [$result]`] is
[$matrix * $vector == $result ?  'true' : 'false']:

[`[$matrix] \cdot [$vector] = [$result2]`] is
[$matrix * $vector == $result2 ?  'true' : 'false']:
END_PGML

ENDDOCUMENT();

That problem renders the same for both the develop branch and this pull request, and the last comparison is an error in both cases. So I must be missing something as to what this is doing.

[Alex-Jordan]

Here is a MWE that works in 2.19 and works on this PR's branch. But on develop, gives an error:

DOCUMENT();

loadMacros(qw(PGstandard.pl PGML.pl));

Context("Matrix");
$M = Matrix([1,2], [3,4]);
$s = Vector("<1,2>");
$Ms = $M*$s;
$b = Matrix(0,0)->transpose;

if ($Ms == $b || $Ms != $b) {
BEGIN_PGML
No error!

END_PGML
};

ENDDOCUMENT();