pr #36030: silence some Singular messages

Author: jhpalmieri

src/sage/rings/polynomial/multi_polynomial_libsingular.pyx

@@ -5757,24 +5757,23 @@ cdef class MPolynomial_libsingular(MPolynomial_libsingular_base):
         else:
             return self * self.denominator()
 
-    def in_subalgebra(self, J, algorithm=None):
+    def in_subalgebra(self, J, algorithm="algebra_containment"):
         """
         Return whether this polynomial is contained in the subalgebra
         generated by ``J``
 
         INPUT:
 
-        - ``J`` -- iterable of elements of the parent polynomial ring
+        - ``J`` -- list of elements of the parent polynomial ring
 
         - ``algorithm`` -- can be ``None`` (the default), "algebra_containment",
           "inSubring", or "groebner".
 
-          - ``None`` (the default): use "algebra_containment".
-
-          - "algebra_containment": use Singular's ``algebra_containment`` function,
+          - "algebra_containment" (default): use Singular's
+            ``algebra_containment`` function,
             https://www.singular.uni-kl.de/Manual/4-2-1/sing_1247.htm#SEC1328. The
-            Singular documentation suggests that this is frequently faster than the
-            next option.
+            Singular documentation suggests that this is frequently
+            faster than the next option.
 
           - "inSubring": use Singular's ``inSubring`` function,
             https://www.singular.uni-kl.de/Manual/4-2-0/sing_1240.htm#SEC1321.
@@ -5789,31 +5788,37 @@ cdef class MPolynomial_libsingular(MPolynomial_libsingular_base):
             and only if the remainder involves only the new variables
             `z_i`.
 
-        Note: the default algorithm may print some intermediate information.
-
         EXAMPLES::
 
             sage: P.<x,y,z> = QQ[]
             sage: J = [x^2 + y^2, x^2 + z^2]
             sage: (y^2).in_subalgebra(J)
-            ...
             False
             sage: a = (x^2 + y^2) * (x^2 + z^2)
             sage: a.in_subalgebra(J, algorithm='inSubring')
             True
             sage: (a^2).in_subalgebra(J, algorithm='groebner')
             True
             sage: (a + a^2).in_subalgebra(J)
-            ...
             True
         """
         R = self.parent()
-        if algorithm is not None:
-            algorithm = algorithm.lower()
+        algorithm = algorithm.lower()
         from sage.libs.singular.function import singular_function, lib as singular_lib
         singular_lib('algebra.lib')
-        if algorithm is None or algorithm == "algebra_containment":
-            return singular_function('algebra_containment')(self, R.ideal(J)) == 1
+        if algorithm == "algebra_containment":
+            execute = singular_function('execute')
+            try:
+                get_printlevel = singular_function('get_printlevel')
+            except NameError:
+                execute('proc get_printlevel {return (printlevel);}')
+                get_printlevel = singular_function('get_printlevel')
+            # It's fairly verbose unless printlevel is -1.
+            saved_printlevel = get_printlevel()
+            execute('printlevel=-1')
+            contains = singular_function('algebra_containment')(self, R.ideal(J)) == 1
+            execute('printlevel={}'.format(saved_printlevel))
+            return contains
         elif algorithm == "insubring":
             return singular_function('inSubring')(self, R.ideal(J))[0] == 1
         elif algorithm == "groebner":