From fe5090687352f1f28712d5f84f3d22c8b070bcee Mon Sep 17 00:00:00 2001
From: Lorenz Panny <lorenz@yx7.cc>
Date: Tue, 20 Dec 2022 15:40:30 +0800
Subject: [PATCH] fix doctests

---
 src/sage/geometry/polyhedron/ppl_lattice_polytope.py | 6 +++---
 src/sage/matrix/matrix2.pyx                          | 4 ----
 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/src/sage/geometry/polyhedron/ppl_lattice_polytope.py b/src/sage/geometry/polyhedron/ppl_lattice_polytope.py
index d45f8a3991a..7b8d712c33b 100644
--- a/src/sage/geometry/polyhedron/ppl_lattice_polytope.py
+++ b/src/sage/geometry/polyhedron/ppl_lattice_polytope.py
@@ -855,8 +855,8 @@ def base_projection_matrix(self, fiber):
             sage: poly = LatticePolytope_PPL((-9,-6,-1,-1),(0,0,0,1),(0,0,1,0),(0,1,0,0),(1,0,0,0))
             sage: fiber = next(poly.fibration_generator(2))
             sage: poly.base_projection_matrix(fiber)
-            [0 0 1 0]
-            [0 0 0 1]
+            [ 0  0 -1  0]
+            [ 0  0  0 -1]
 
         Note that the basis choice in :meth:`base_projection` for the
         quotient is usually different::
@@ -866,7 +866,7 @@ def base_projection_matrix(self, fiber):
             sage: [ proj(p) for p in poly.integral_points() ]
             [(-1, -1), (0, 0), (0, 0), (0, 0), (0, 0), (0, 0), (0, 0), (0, 0), (0, 1), (1, 0)]
             sage: [ proj_matrix*p for p in poly.integral_points() ]
-            [(-1, -1), (0, 0), (0, 0), (0, 0), (0, 0), (0, 0), (0, 0), (0, 0), (0, 1), (1, 0)]
+            [(1, 1), (0, 0), (0, 0), (0, 0), (0, 0), (0, 0), (0, 0), (0, 0), (0, -1), (-1, 0)]
         """
         return matrix(ZZ, fiber.vertices()).right_kernel_matrix()
 
diff --git a/src/sage/matrix/matrix2.pyx b/src/sage/matrix/matrix2.pyx
index 6150cc68ad5..f3af339befd 100644
--- a/src/sage/matrix/matrix2.pyx
+++ b/src/sage/matrix/matrix2.pyx
@@ -4405,10 +4405,6 @@ cdef class Matrix(Matrix1):
             Traceback (most recent call last):
             ...
             ValueError: 'pari' matrix kernel algorithm only available over non-trivial number fields and the integers, not over Rational Field
-            sage: matrix(Integers(6), 2, 2).right_kernel_matrix(algorithm='generic')
-            Traceback (most recent call last):
-            ...
-            NotImplementedError: Echelon form not implemented over 'Ring of integers modulo 6'.
             sage: matrix(QQ, 2, 2).right_kernel_matrix(algorithm='pluq')
             Traceback (most recent call last):
             ...