added set_seed support for singular

src/sage/misc/randstate.pxd

@@ -10,6 +10,8 @@ cdef class randstate:
 
     cdef object _gp_saved_seeds
 
+    cdef object _singular_saved_seed
+
     cpdef set_seed_libc(self, bint force)
     cpdef set_seed_ntl(self, bint force)
 

src/sage/misc/randstate.pyx

@@ -439,6 +439,7 @@ cdef randstate _current_randstate
 cdef randstate _libc_seed_randstate
 cdef randstate _ntl_seed_randstate
 cdef randstate _gap_seed_randstate
+cdef randstate _singular_seed_randstate
 cdef randstate _pari_seed_randstate
 # For each gp subprocess that has been seeded, keep track of which
 # randstate object was the most recent one to seed it.
@@ -707,6 +708,40 @@ cdef class randstate:
 
              _gap_seed_randstate = self
 
+     def set_seed_singular(self):
+         r"""
+         Checks to see if ``self`` was the most recent :class:`randstate`
+         to seed the Singular random number generator.  If not, seeds
+         the generator.
+
+         EXAMPLES::
+
+             sage: set_random_seed(0)
+             sage: current_randstate().set_seed_singular()
+             sage: singular.random(1, 100)
+             90
+             sage: singular.random(1, 100)
+             21
+         """
+         global _singular_seed_randstate
+         if _singular_seed_randstate is not self:
+             from sage.interfaces.singular import singular
+
+             if self._singular_saved_seed is not None:
+                 seed = self.singular_saved_seed
+             else:
+                 import sage.rings.integer_ring as integer_ring
+                 from sage.rings.integer_ring import ZZ
+                 seed = ZZ.random_element(long(1)<<30)
+
+             # reset the seed in Singular
+             singular.eval('system("--random",%d)' % seed)
+
+             if _singular_seed_randstate is not None:
+                 _singular_seed_randstate._singular_saved_seed = seed
+
+             _singular_seed_randstate = self
+
      def set_seed_gp(self, gp=None):
          r"""
          Checks to see if ``self`` was the most recent :class:`randstate`