add DomainError for real_roots and complex_roots for positive characteristic univariate polys

Author: GiacomoPope

src/flint/flint_base/flint_base.pyx

@@ -254,6 +254,9 @@ cdef class flint_poly(flint_elem):
                 roots.append((v, m))
         return roots
 
+    def real_roots(self):
+        raise AttributeError("Complex roots are not supported for this polynomial")
+
     def complex_roots(self):
         raise AttributeError("Complex roots are not supported for this polynomial")
 

src/flint/test/test_all.py

@@ -1465,6 +1465,9 @@ def set_bad2():
     assert P([1], 11).roots() == []
     assert P([1, 2, 3], 11).roots() == [(8, 1), (6, 1)]
     assert P([1, 6, 1, 8], 11).roots() == [(5, 3)]
+    assert raises(lambda: P([1, 2, 3], 11).real_roots(), DomainError)
+    assert raises(lambda: P([1, 2, 3], 11).complex_roots(), DomainError)
+
 
 def test_nmod_mat():
     M = flint.nmod_mat
@@ -2226,12 +2229,15 @@ def test_fmpz_mod_poly():
         assert set(ff.factor()[1]) == set(ff.factor(algorithm="kaltofen_shoup")[1])
         assert set(ff.factor()[1]) == set(ff.factor(algorithm="berlekamp")[1])
         assert raises(lambda: R_test([0,0,1]).factor(algorithm="AAA"), ValueError)
+        assert raises(lambda: R_test([0,0,1]).real_roots(), DomainError)
         assert raises(lambda: R_test([0,0,1]).complex_roots(), DomainError)
 
+
         # composite moduli not supported
         assert raises(lambda: R_cmp([0,0,1]).factor(), NotImplementedError)
         assert raises(lambda: R_cmp([0,0,1]).factor_squarefree(), NotImplementedError)
         assert raises(lambda: R_cmp([0,0,1]).roots(), NotImplementedError)
+        assert raises(lambda: R_cmp([0,0,1]).real_roots(), DomainError)
         assert raises(lambda: R_cmp([0,0,1]).complex_roots(), DomainError)
 
         # minpoly
@@ -4020,7 +4026,6 @@ def test_fq_default_poly():
         assert raises(lambda: f / "AAA", TypeError)
         assert raises(lambda: "AAA" / f, TypeError)
 
-
         # ZeroDivisionError
         assert raises(lambda: f / 0, ZeroDivisionError)
         assert raises(lambda: f // 0, ZeroDivisionError)
@@ -4053,6 +4058,9 @@ def test_fq_default_poly():
         # pow_mod
         assert f.pow_mod(2, g) == (f*f) % g
         assert raises(lambda: f.pow_mod(2, "AAA"), TypeError)
+
+        # roots
+        assert raises(lambda: f.real_roots(), DomainError)
         assert raises(lambda: f.complex_roots(), DomainError)
 
         # compose errors

src/flint/types/fmpz_mod_poly.pyx

@@ -1864,6 +1864,13 @@ cdef class fmpz_mod_poly(flint_poly):
                 res[i] = root
         return res
 
+    def real_roots(self):
+        """
+        This method is not implemented for polynomials in
+        :math:`(\mathbb{Z}/N\mathbb{Z})[X]`
+        """
+        raise DomainError("Cannot compute real roots for polynomials over integers modulo N")
+
     def complex_roots(self):
         """
         This method is not implemented for polynomials in

src/flint/types/fq_default_poly.pyx

@@ -1588,6 +1588,12 @@ cdef class fq_default_poly(flint_poly):
                 res[i] = root
         return res
 
+    def real_roots(self):
+        """
+        This method is not implemented for polynomials in finite fields
+        """
+        raise DomainError("Cannot compute real roots for polynomials over finite fields")
+
     def complex_roots(self):
         """
         This method is not implemented for polynomials in finite fields

src/flint/types/nmod_poly.pyx

@@ -668,3 +668,17 @@ cdef class nmod_poly(flint_poly):
             nmod_poly_init(v.val, self.val.mod.n)
             nmod_poly_deflate(v.val, self.val, n)
             return v, int(n)
+
+    def real_roots(self):
+        """
+        This method is not implemented for polynomials in
+        :math:`(\mathbb{Z}/N\mathbb{Z})[X]`
+        """
+        raise DomainError("Cannot compute real roots for polynomials over integers modulo N")
+
+    def complex_roots(self):
+        """
+        This method is not implemented for polynomials in
+        :math:`(\mathbb{Z}/N\mathbb{Z})[X]`
+        """
+        raise DomainError("Cannot compute complex roots for polynomials over integers modulo N")