From e9758859568d510f8a42131ee0fed29a1d6b8c53 Mon Sep 17 00:00:00 2001
From: Alex Jordan <alex.jordan@pcc.edu>
Date: Wed, 10 Jun 2026 23:29:39 -0700
Subject: [PATCH] don't try to remove a Matrix's only row (or only column)

---
 lib/Value/Matrix.pm     |  2 ++
 t/math_objects/matrix.t | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/lib/Value/Matrix.pm b/lib/Value/Matrix.pm
index 9a6c41f70..277d92f83 100644
--- a/lib/Value/Matrix.pm
+++ b/lib/Value/Matrix.pm
@@ -1502,6 +1502,7 @@ sub removeRow {
 	my @dim    = $self->dimensions;
 	my $degree = scalar @dim;
 	Value::Error("removeRow cannot be used on a Matrix of degree 1") if $degree == 1;
+	Value::Error("cannot remove a Matrix's only row")                if $dim[0] == 1;
 	my @indices = map { [ 1 .. $_ ] } @dim;
 	Value::Error("Can only remove rows 1 through $indices[0][-1]")
 		unless $r =~ /^\d+$/ && $r >= 1 && $r <= $indices[0][-1];
@@ -1529,6 +1530,7 @@ sub removeColumn {
 	my @dim    = $self->dimensions;
 	my $degree = scalar @dim;
 	Value::Error("removeColumn cannot be used on a Matrix of degree 1") if $degree == 1;
+	Value::Error("cannot remove a Matrix's only column")                if $dim[1] == 1;
 	my @indices = map { [ 1 .. $_ ] } @dim;
 	Value::Error("Can only remove columns 1 through $indices[1][-1]")
 		unless $r =~ /^\d+$/ && $r >= 1 && $r <= $indices[1][-1];
diff --git a/t/math_objects/matrix.t b/t/math_objects/matrix.t
index 0fcd83a4e..c793daa31 100644
--- a/t/math_objects/matrix.t
+++ b/t/math_objects/matrix.t
@@ -334,6 +334,11 @@ subtest 'Remove row' => sub {
 	like dies {
 		$A->removeRow('a');
 	}, qr/Can only remove rows 1 through 4/, 'check that error is thrown for bad row specification';
+
+	my $D = Matrix([ [ 1, 2, 3 ] ]);
+	like dies {
+		$D->removeRow(1);
+	}, qr/cannot remove a Matrix's only row/, 'check that error is thrown for trying to remove the only row';
 };
 
 subtest 'Remove column' => sub {
@@ -362,6 +367,11 @@ subtest 'Remove column' => sub {
 	like dies {
 		$A->removeColumn('a');
 	}, qr/Can only remove columns 1 through 4/, 'check that error is thrown for bad column specification';
+
+	my $D = Matrix([1], [2], [3]);
+	like dies {
+		$D->removeColumn(1);
+	}, qr/cannot remove a Matrix's only column/, 'check that error is thrown for trying to remove the only column';
 };
 
 subtest 'Construct an identity matrix' => sub {