Merge pull request #1309 from skirpichev/misc

Misc fixes

.git_archival.txt

@@ -0,0 +1,4 @@
+node: $Format:%H$
+node-date: $Format:%cI$
+describe-name: $Format:%(describe:tags=true,match=*[0-9]*)$
+ref-names: $Format:%D$

.gitattributes

@@ -6,3 +6,4 @@
 *.yaml  text
 *.cnf   text
 *.bib   text
+.git_archival.txt  export-subst

diofant/core/function.py

@@ -1195,6 +1195,8 @@ def free_symbols(self):
         return self.expr.free_symbols
 
     def _eval_subs(self, old, new):
+        from .symbol import Dummy
+
         if old in self.variables and not new._diff_wrt:
             # issue sympy/sympy#4719
             return Subs(self, (old, new))
@@ -1214,7 +1216,24 @@ def _subset(a, b):
             if _subset(old_vars, self_vars):
                 return Derivative(new, *(self_vars - old_vars).elements())
 
-        return Derivative(*(x._subs(old, new) for x in self.args))
+        args = list(self.args)
+        newargs = [x._subs(old, new) for x in args]
+
+        if newargs[0] != args[0] and not isinstance(old, UndefinedFunction):
+            # Can't change expr by introducing something that is in
+            # the variables if it was already in the expr.
+            # E.g. for Derivative(f(x, g(y)), y), x cannot be replaced with
+            # anything that has y in it; for f(g(x), g(y)).diff(g(y))
+            # g(x) cannot be replaced with anything that has g(y).
+            syms = {vi: Dummy() for vi in self.variables if not vi.is_Symbol}
+            wrt = {syms.get(vi, vi) for vi in self.variables}
+            forbidden = args[0].xreplace(syms).free_symbols & wrt
+            nfree = new.xreplace(syms).free_symbols
+            ofree = old.xreplace(syms).free_symbols
+            if (nfree - ofree) & forbidden:
+                return Subs(self, (old, new))
+
+        return Derivative(*newargs)
 
     def _eval_nseries(self, x, n, logx):
         arg = self.expr.nseries(x, n, logx)

diofant/tests/calculus/test_order.py

@@ -166,7 +166,7 @@ def test_leading_order2():
 
 
 def test_order_leadterm():
-    assert O(x**2)._eval_as_leading_term(x) == O(x**2)
+    assert O(x**2).as_leading_term(x) == O(x**2)
 
 
 def test_order_symbols():

diofant/tests/core/test_arit.py

@@ -535,7 +535,6 @@ def test_Mul_is_negative_positive():
     assert (-neg).is_negative is False
     assert (2*neg).is_negative is True
 
-    assert (2*pos)._eval_is_negative() is False
     assert (2*pos).is_negative is False
 
     assert pos.is_negative is False

diofant/tests/core/test_function.py

@@ -100,9 +100,9 @@ def test_diff_symbols():
     assert diff(f(x, y, z), x, y, (z, 2)) == Derivative(f(x, y, z), x, y, z, z)
     assert diff(f(x, y, z), x, y, (z, 2), evaluate=False) == \
         Derivative(f(x, y, z), x, y, z, z)
-    assert Derivative(f(x, y, z), x, y, z)._eval_derivative(z) == \
+    assert Derivative(f(x, y, z), x, y, z).diff(z) == \
         Derivative(f(x, y, z), x, y, z, z)
-    assert Derivative(Derivative(f(x, y, z), x), y)._eval_derivative(z) == \
+    assert Derivative(Derivative(f(x, y, z), x), y).diff(z) == \
         Derivative(f(x, y, z), x, y, z)
 
 
@@ -398,25 +398,25 @@ def test_function_complex():
 def test_function__eval_nseries():
     n = Symbol('n')
 
-    assert sin(x)._eval_nseries(x, 2, None) == x + O(x**3)
-    assert sin(x + 1)._eval_nseries(x, 2, None) == x*cos(1) + sin(1) + O(x**2)
-    assert sin(pi*(1 - x))._eval_nseries(x, 2, None) == pi*x + O(x**3)
-    assert acos(1 - x**2)._eval_nseries(x, 2, None) == sqrt(2)*x + O(x**2)
-    assert polygamma(n, x + 1)._eval_nseries(x, 2, None) == \
+    assert sin(x).series(x, n=3) == x + O(x**3)
+    assert sin(x + 1).series(x, n=2) == x*cos(1) + sin(1) + O(x**2)
+    assert sin(pi*(1 - x)).series(x, n=3) == pi*x + O(x**3)
+    assert acos(1 - x**2).series(x, n=2) == sqrt(2)*x + O(x**2)
+    assert polygamma(n, x + 1).series(x, n=2) == \
         polygamma(n, 1) + polygamma(n + 1, 1)*x + O(x**2)
-    pytest.raises(PoleError, lambda: sin(1/x)._eval_nseries(x, 2, None))
-    assert acos(1 - x)._eval_nseries(x, 4, None) == sqrt(2)*sqrt(x) + \
+    pytest.raises(PoleError, lambda: sin(1/x).series(x, n=2))
+    assert acos(1 - x).series(x, n=2) == sqrt(2)*sqrt(x) + \
         sqrt(2)*x**Rational(3, 2)/12 + O(x**2)
-    assert acos(1 + x)._eval_nseries(x, 4, None) == sqrt(2)*I*sqrt(x) - \
+    assert acos(1 + x).series(x, n=2) == sqrt(2)*I*sqrt(x) - \
         sqrt(2)*I*x**(3/2)/12 + O(x**2)
-    assert loggamma(1/x)._eval_nseries(x, 0, None) == O(1/x) - log(x)/x
+    assert loggamma(1/x).series(x, n=-1) == O(1/x) - log(x)/x
     assert loggamma(log(1/x)).series(x, n=1, logx=y) == loggamma(-y)
 
     # issue sympy/sympy#6725:
-    assert expint(Rational(3, 2), -x)._eval_nseries(x, 8, None) == \
+    assert expint(Rational(3, 2), -x).series(x, n=5) == \
         2 - 2*I*sqrt(pi)*sqrt(x) - 2*x - x**2/3 - x**3/15 - x**4/84 + O(x**5)
-    assert sin(sqrt(x))._eval_nseries(x, 6, None) == \
-        sqrt(x) - x**Rational(3, 2)/6 + x**Rational(5, 2)/120 + O(x**Rational(7, 2))
+    assert sin(sqrt(x)).series(x, n=3) == \
+        sqrt(x) - x**Rational(3, 2)/6 + x**Rational(5, 2)/120 + O(x**3)
 
 
 def test_doit():

diofant/tests/core/test_subs.py

@@ -421,7 +421,6 @@ def test_functions_subs():
 
 
 def test_derivative_subs():
-    y = Symbol('y')
     f = Function('f')
     assert Derivative(f(x), x).subs({f(x): y}) != 0
     assert Derivative(f(x), x).subs({f(x): y}).subs({y: f(x)}) == \
@@ -430,6 +429,10 @@ def test_derivative_subs():
     assert cse(Derivative(f(x), x) + f(x))[1][0].has(Derivative)
     assert cse(Derivative(f(x, y), x) +
                Derivative(f(x, y), y))[1][0].has(Derivative)
+    # issue diofant/diofant#1303
+    g = Function('g')
+    d = f(x, y, z).diff(x)
+    assert d.subs({y: g(x, z)}) == Subs(d, (y, g(x, z)))
 
 
 def test_derivative_subs2():

diofant/tests/functions/test_gamma_functions.py

@@ -399,13 +399,13 @@ def test_loggamma():
     assert loggamma(w).is_extended_real is None
 
     def tN(N, M):
-        assert loggamma(1/x)._eval_nseries(x, N, None).getn() == M
-    tN(0, -1)
-    tN(1, +1)
-    tN(2, +3)
-    tN(3, +3)
-    tN(4, +5)
-    tN(5, +5)
+        assert loggamma(1/x).series(x, n=N).getn() == M
+    tN(-1, -1)
+    tN(1, 1)
+    tN(2, 2)
+    tN(3, 3)
+    tN(4, 4)
+    tN(5, 5)
 
 
 def test_polygamma_expansion():

diofant/tests/simplify/test_simplify.py

@@ -117,10 +117,10 @@ def test_simplify_other():
 
 
 def test_simplify_complex():
-    cosAsExp = cos(x)._eval_rewrite_as_exp(x)
-    tanAsExp = tan(x)._eval_rewrite_as_exp(x)
-    assert simplify(cosAsExp*tanAsExp).expand() == (
-        sin(x))._eval_rewrite_as_exp(x).expand()  # issue sympy/sympy#4341
+    cosAsExp = cos(x).rewrite(exp)
+    tanAsExp = tan(x).rewrite(exp)
+    # issue sympy/sympy#4341
+    assert simplify(cosAsExp*tanAsExp).expand() == sin(x).rewrite(exp).expand()
 
 
 def test_simplify_ratio():

diofant/tests/solvers/test_ode.py

@@ -3047,3 +3047,21 @@ def test_sympyissue_23562():
 def test_sympyissue_23702():
     assert dsolve(f(x).diff(x) - f(x), f(x),
                   init={f(0): f(0)}) == Eq(f(x),  f(0)*exp(x))
+
+
+def test_sympyissue_24957():
+    eq = (2*x**3 + 3*f(x)) + (3*x + f(x) - 1)*f(x).diff(x)
+    assert dsolve(eq) == [Eq(f(x), -3*x - sqrt(C1 - x**4 + 9*x**2 - 6*x) + 1),
+                          Eq(f(x), -3*x + sqrt(C1 - x**4 + 9*x**2 - 6*x) + 1)]
+
+
+def test_sympyissue_24955():
+    eq = x**2*f(x).diff(x) - f(x)**2*f(x).diff(x) + 2*x*f(x)
+    assert dsolve(eq) == [Eq(f(x), root(2, 3)*(-x**2/root(3*C1 + sqrt(9*C1**2 - 4*x**6), 3) -
+                             root(2, 3)*root(3*C1 + sqrt(9*C1**2 - 4*x**6), 3)/2)),
+                          Eq(f(x), root(2, 3)*(2*x**2/((1 + sqrt(3)*I)*root(3*C1 + sqrt(9*C1**2 - 4*x**6), 3)) +
+                             root(2, 3)*root(3*C1 + sqrt(9*C1**2 - 4*x**6), 3)/4 +
+                             root(2, 3)*sqrt(3)*I*root(3*C1 + sqrt(9*C1**2 - 4*x**6), 3)/4)),
+                          Eq(f(x), root(2, 3)*(-2*x**2/((-1 + sqrt(3)*I)*root(3*C1 + sqrt(9*C1**2 - 4*x**6), 3)) +
+                             root(2, 3)*root(3*C1 + sqrt(9*C1**2 - 4*x**6), 3)/4 -
+                             root(2, 3)*sqrt(3)*I*root(3*C1 + sqrt(9*C1**2 - 4*x**6), 3)/4))]

docs/release/notes-0.14.rst

@@ -129,3 +129,5 @@ These Sympy issues also were addressed:
 * :sympyissue:`24477`: Expand before integrate gives different results with big O
 * :sympyissue:`24928`: simplify(asinh(2)-oo)->0
 * :sympyissue:`24948`: .is_positive returns None when it should be False
+* :sympyissue:`24957`: Timeout for dsolve((2x^3+3y)+(3x+y-1)y'=0)
+* :sympyissue:`24955`: Timeout for dsolve(x^2*y'-y^2*y'+2*x*y=0)