def test_diopcoverage(): eq = (2 * x + y + 1)**2 assert diop_solve(eq) == {(t_0, -2 * t_0 - 1)} eq = 2 * x**2 + 6 * x * y + 12 * x + 4 * y**2 + 18 * y + 18 assert diop_solve(eq) == {(t, -t - 3), (2 * t - 3, -t)} assert diop_quadratic(x + y**2 - 3) == {(-t**2 + 3, -t)} assert diop_linear(x + y - 3) == (t_0, 3 - t_0) assert base_solution_linear(0, 1, 2, t=None) == (0, 0) ans = (3 * t - 1, -2 * t + 1) assert base_solution_linear(4, 8, 12, t) == ans assert base_solution_linear(4, 8, 12, t=None) == tuple(_.subs(t, 0) for _ in ans) assert cornacchia(1, 1, 20) is None assert cornacchia(1, 1, 5) == {(2, 1)} assert cornacchia(1, 2, 17) == {(3, 2)} raises(ValueError, lambda: reconstruct(4, 20, 1)) assert gaussian_reduce(4, 1, 3) == (1, 1) eq = -w**2 - x**2 - y**2 + z**2 assert diop_general_pythagorean(eq) == \ diop_general_pythagorean(-eq) == \ (m1**2 + m2**2 - m3**2, 2*m1*m3, 2*m2*m3, m1**2 + m2**2 + m3**2) assert len(check_param(S(3) + x / 3, S(4) + x / 2, S(2), [x])) == 0 assert len(check_param(Rational(3, 2), S(4) + x, S(2), [x])) == 0 assert len(check_param(S(4) + x, Rational(3, 2), S(2), [x])) == 0 assert _nint_or_floor(16, 10) == 2 assert _odd(1) == (not _even(1)) == True assert _odd(0) == (not _even(0)) == False assert _remove_gcd(2, 4, 6) == (1, 2, 3) raises(TypeError, lambda: _remove_gcd((2, 4, 6))) assert sqf_normal(2*3**2*5, 2*5*11, 2*7**2*11) == \ (11, 1, 5) # it's ok if these pass some day when the solvers are implemented raises(NotImplementedError, lambda: diophantine(x**2 + y**2 + x * y + 2 * y * z - 12)) raises(NotImplementedError, lambda: diophantine(x**3 + y**2)) assert diop_quadratic(x**2 + y**2 - 1**2 - 3**4) == \ {(-9, -1), (-9, 1), (-1, -9), (-1, 9), (1, -9), (1, 9), (9, -1), (9, 1)}
def intersection_sets(a, b): # noqa:F811 from sympy.solvers.diophantine.diophantine import diop_linear from sympy.core.numbers import ilcm from sympy import sign # non-overlap quick exits if not b: return S.EmptySet if not a: return S.EmptySet if b.sup < a.inf: return S.EmptySet if b.inf > a.sup: return S.EmptySet # work with finite end at the start r1 = a if r1.start.is_infinite: r1 = r1.reversed r2 = b if r2.start.is_infinite: r2 = r2.reversed # If both ends are infinite then it means that one Range is just the set # of all integers (the step must be 1). if r1.start.is_infinite: return b if r2.start.is_infinite: return a # this equation represents the values of the Range; # it's a linear equation eq = lambda r, i: r.start + i * r.step # we want to know when the two equations might # have integer solutions so we use the diophantine # solver va, vb = diop_linear(eq(r1, Dummy('a')) - eq(r2, Dummy('b'))) # check for no solution no_solution = va is None and vb is None if no_solution: return S.EmptySet # there is a solution # ------------------- # find the coincident point, c a0 = va.as_coeff_Add()[0] c = eq(r1, a0) # find the first point, if possible, in each range # since c may not be that point def _first_finite_point(r1, c): if c == r1.start: return c # st is the signed step we need to take to # get from c to r1.start st = sign(r1.start - c) * step # use Range to calculate the first point: # we want to get as close as possible to # r1.start; the Range will not be null since # it will at least contain c s1 = Range(c, r1.start + st, st)[-1] if s1 == r1.start: pass else: # if we didn't hit r1.start then, if the # sign of st didn't match the sign of r1.step # we are off by one and s1 is not in r1 if sign(r1.step) != sign(st): s1 -= st if s1 not in r1: return return s1 # calculate the step size of the new Range step = abs(ilcm(r1.step, r2.step)) s1 = _first_finite_point(r1, c) if s1 is None: return S.EmptySet s2 = _first_finite_point(r2, c) if s2 is None: return S.EmptySet # replace the corresponding start or stop in # the original Ranges with these points; the # result must have at least one point since # we know that s1 and s2 are in the Ranges def _updated_range(r, first): st = sign(r.step) * step if r.start.is_finite: rv = Range(first, r.stop, st) else: rv = Range(r.start, first + st, st) return rv r1 = _updated_range(a, s1) r2 = _updated_range(b, s2) # work with them both in the increasing direction if sign(r1.step) < 0: r1 = r1.reversed if sign(r2.step) < 0: r2 = r2.reversed # return clipped Range with positive step; it # can't be empty at this point start = max(r1.start, r2.start) stop = min(r1.stop, r2.stop) return Range(start, stop, step)