from sympy import ( adjoint, And, Basic, conjugate, diff, expand, Eq, Function, I, ITE, Integral, integrate, Interval, KroneckerDelta, lambdify, log, Max, Min, oo, Or, pi, Piecewise, piecewise_fold, Rational, solve, symbols, transpose, cos, sin, exp, Abs, Ne, Not, Symbol, S, sqrt, Sum, Tuple, zoo, Float, DiracDelta, Heaviside, Add, Mul, factorial, Ge, Contains) from sympy.core.expr import unchanged from sympy.functions.elementary.piecewise import Undefined, ExprCondPair from sympy.printing import srepr from sympy.testing.pytest import raises, slow from sympy.simplify import simplify a, b, c, d, x, y = symbols('a:d, x, y') z = symbols('z', nonzero=True) def test_piecewise1(): # Test canonicalization assert unchanged(Piecewise, ExprCondPair(x, x < 1), ExprCondPair(0, True)) assert Piecewise((x, x < 1), (0, True)) == Piecewise(ExprCondPair(x, x < 1), ExprCondPair(0, True)) assert Piecewise((x, x < 1), (0, True), (1, True)) == \ Piecewise((x, x < 1), (0, True)) assert Piecewise((x, x < 1), (0, False), (-1, 1 > 2)) == \ Piecewise((x, x < 1)) assert Piecewise((x, x < 1), (0, x < 1), (0, True)) == \ Piecewise((x, x < 1), (0, True)) assert Piecewise((x, x < 1), (0, x < 2), (0, True)) == \ Piecewise((x, x < 1), (0, True)) assert Piecewise((x, x < 1), (x, x < 2), (0, True)) == \ Piecewise((x, Or(x < 1, x < 2)), (0, True)) assert Piecewise((x, x < 1), (x, x < 2), (x, True)) == x assert Piecewise((x, True)) == x # Explicitly constructed empty Piecewise not accepted raises(TypeError, lambda: Piecewise()) # False condition is never retained assert Piecewise((2*x, x < 0), (x, False)) == \ Piecewise((2*x, x < 0), (x, False), evaluate=False) == \ Piecewise((2*x, x < 0)) assert Piecewise((x, False)) == Undefined raises(TypeError, lambda: Piecewise(x)) assert Piecewise((x, 1)) == x # 1 and 0 are accepted as True/False raises(TypeError, lambda: Piecewise((x, 2))) raises(TypeError, lambda: Piecewise((x, x**2))) raises(TypeError, lambda: Piecewise(([1], True))) assert Piecewise(((1, 2), True)) == Tuple(1, 2) cond = (Piecewise((1, x < 0), (2, True)) < y) assert Piecewise((1, cond) ) == Piecewise((1, ITE(x < 0, y > 1, y > 2))) assert Piecewise((1, x > 0), (2, And(x <= 0, x > -1)) ) == Piecewise((1, x > 0), (2, x > -1)) # test for supporting Contains in Piecewise pwise = Piecewise( (1, And(x <= 6, x > 1, Contains(x, S.Integers))), (0, True)) assert pwise.subs(x, pi) == 0 assert pwise.subs(x, 2) == 1 assert pwise.subs(x, 7) == 0 # Test subs p = Piecewise((-1, x < -1), (x**2, x < 0), (log(x), x >= 0)) p_x2 = Piecewise((-1, x**2 < -1), (x**4, x**2 < 0), (log(x**2), x**2 >= 0)) assert p.subs(x, x**2) == p_x2 assert p.subs(x, -5) == -1 assert p.subs(x, -1) == 1 assert p.subs(x, 1) == log(1) # More subs tests p2 = Piecewise((1, x < pi), (-1, x < 2*pi), (0, x > 2*pi)) p3 = Piecewise((1, Eq(x, 0)), (1/x, True)) p4 = Piecewise((1, Eq(x, 0)), (2, 1/x>2)) assert p2.subs(x, 2) == 1 assert p2.subs(x, 4) == -1 assert p2.subs(x, 10) == 0 assert p3.subs(x, 0.0) == 1 assert p4.subs(x, 0.0) == 1 f, g, h = symbols('f,g,h', cls=Function) pf = Piecewise((f(x), x < -1), (f(x) + h(x) + 2, x <= 1)) pg = Piecewise((g(x), x < -1), (g(x) + h(x) + 2, x <= 1)) assert pg.subs(g, f) == pf assert Piecewise((1, Eq(x, 0)), (0, True)).subs(x, 0) == 1 assert Piecewise((1, Eq(x, 0)), (0, True)).subs(x, 1) == 0 assert Piecewise((1, Eq(x, y)), (0, True)).subs(x, y) == 1 assert Piecewise((1, Eq(x, z)), (0, True)).subs(x, z) == 1 assert Piecewise((1, Eq(exp(x), cos(z))), (0, True)).subs(x, z) == \ Piecewise((1, Eq(exp(z), cos(z))), (0, True)) p5 = Piecewise( (0, Eq(cos(x) + y, 0)), (1, True)) assert p5.subs(y, 0) == Piecewise( (0, Eq(cos(x), 0)), (1, True)) assert Piecewise((-1, y < 1), (0, x < 0), (1, Eq(x, 0)), (2, True) ).subs(x, 1) == Piecewise((-1, y < 1), (2, True)) assert Piecewise((1, Eq(x**2, -1)), (2, x < 0)).subs(x, I) == 1 p6 = Piecewise((x, x > 0)) n = symbols('n', negative=True) assert p6.subs(x, n) == Undefined # Test evalf assert p.evalf() == p assert p.evalf(subs={x: -2}) == -1 assert p.evalf(subs={x: -1}) == 1 assert p.evalf(subs={x: 1}) == log(1) assert p6.evalf(subs={x: -5}) == Undefined # Test doit f_int = Piecewise((Integral(x, (x, 0, 1)), x < 1)) assert f_int.doit() == Piecewise( (S.Half, x < 1) ) # Test differentiation f = x fp = x*p dp = Piecewise((0, x < -1), (2*x, x < 0), (1/x, x >= 0)) fp_dx = x*dp + p assert diff(p, x) == dp assert diff(f*p, x) == fp_dx # Test simple arithmetic assert x*p == fp assert x*p + p == p + x*p assert p + f == f + p assert p + dp == dp + p assert p - dp == -(dp - p) # Test power dp2 = Piecewise((0, x < -1), (4*x**2, x < 0), (1/x**2, x >= 0)) assert dp**2 == dp2 # Test _eval_interval f1 = x*y + 2 f2 = x*y**2 + 3 peval = Piecewise((f1, x < 0), (f2, x > 0)) peval_interval = f1.subs( x, 0) - f1.subs(x, -1) + f2.subs(x, 1) - f2.subs(x, 0) assert peval._eval_interval(x, 0, 0) == 0 assert peval._eval_interval(x, -1, 1) == peval_interval peval2 = Piecewise((f1, x < 0), (f2, True)) assert peval2._eval_interval(x, 0, 0) == 0 assert peval2._eval_interval(x, 1, -1) == -peval_interval assert peval2._eval_interval(x, -1, -2) == f1.subs(x, -2) - f1.subs(x, -1) assert peval2._eval_interval(x, -1, 1) == peval_interval assert peval2._eval_interval(x, None, 0) == peval2.subs(x, 0) assert peval2._eval_interval(x, -1, None) == -peval2.subs(x, -1) # Test integration assert p.integrate() == Piecewise( (-x, x < -1), (x**3/3 + Rational(4, 3), x < 0), (x*log(x) - x + Rational(4, 3), True)) p = Piecewise((x, x < 1), (x**2, -1 <= x), (x, 3 < x)) assert integrate(p, (x, -2, 2)) == Rational(5, 6) assert integrate(p, (x, 2, -2)) == Rational(-5, 6) p = Piecewise((0, x < 0), (1, x < 1), (0, x < 2), (1, x < 3), (0, True)) assert integrate(p, (x, -oo, oo)) == 2 p = Piecewise((x, x < -10), (x**2, x <= -1), (x, 1 < x)) assert integrate(p, (x, -2, 2)) == Undefined # Test commutativity assert isinstance(p, Piecewise) and p.is_commutative is True def test_piecewise_free_symbols(): f = Piecewise((x, a < 0), (y, True)) assert f.free_symbols == {x, y, a} def test_piecewise_integrate1(): x, y = symbols('x y', real=True, finite=True) f = Piecewise(((x - 2)**2, x >= 0), (1, True)) assert integrate(f, (x, -2, 2)) == Rational(14, 3) g = Piecewise(((x - 5)**5, x >= 4), (f, True)) assert integrate(g, (x, -2, 2)) == Rational(14, 3) assert integrate(g, (x, -2, 5)) == Rational(43, 6) assert g == Piecewise(((x - 5)**5, x >= 4), (f, x < 4)) g = Piecewise(((x - 5)**5, 2 <= x), (f, x < 2)) assert integrate(g, (x, -2, 2)) == Rational(14, 3) assert integrate(g, (x, -2, 5)) == Rational(-701, 6) assert g == Piecewise(((x - 5)**5, 2 <= x), (f, True)) g = Piecewise(((x - 5)**5, 2 <= x), (2*f, True)) assert integrate(g, (x, -2, 2)) == Rational(28, 3) assert integrate(g, (x, -2, 5)) == Rational(-673, 6) def test_piecewise_integrate1b(): g = Piecewise((1, x > 0), (0, Eq(x, 0)), (-1, x < 0)) assert integrate(g, (x, -1, 1)) == 0 g = Piecewise((1, x - y < 0), (0, True)) assert integrate(g, (y, -oo, 0)) == -Min(0, x) assert g.subs(x, -3).integrate((y, -oo, 0)) == 3 assert integrate(g, (y, 0, -oo)) == Min(0, x) assert integrate(g, (y, 0, oo)) == -Max(0, x) + oo assert integrate(g, (y, -oo, 42)) == -Min(42, x) + 42 assert integrate(g, (y, -oo, oo)) == -x + oo g = Piecewise((0, x < 0), (x, x <= 1), (1, True)) gy1 = g.integrate((x, y, 1)) g1y = g.integrate((x, 1, y)) for yy in (-1, S.Half, 2): assert g.integrate((x, yy, 1)) == gy1.subs(y, yy) assert g.integrate((x, 1, yy)) == g1y.subs(y, yy) assert gy1 == Piecewise( (-Min(1, Max(0, y))**2/2 + S.Half, y < 1), (-y + 1, True)) assert g1y == Piecewise( (Min(1, Max(0, y))**2/2 - S.Half, y < 1), (y - 1, True)) @slow def test_piecewise_integrate1ca(): y = symbols('y', real=True) g = Piecewise( (1 - x, Interval(0, 1).contains(x)), (1 + x, Interval(-1, 0).contains(x)), (0, True) ) gy1 = g.integrate((x, y, 1)) g1y = g.integrate((x, 1, y)) assert g.integrate((x, -2, 1)) == gy1.subs(y, -2) assert g.integrate((x, 1, -2)) == g1y.subs(y, -2) assert g.integrate((x, 0, 1)) == gy1.subs(y, 0) assert g.integrate((x, 1, 0)) == g1y.subs(y, 0) assert g.integrate((x, 2, 1)) == gy1.subs(y, 2) assert g.integrate((x, 1, 2)) == g1y.subs(y, 2) assert piecewise_fold(gy1.rewrite(Piecewise)) == \ Piecewise( (1, y <= -1), (-y**2/2 - y + S.Half, y <= 0), (y**2/2 - y + S.Half, y < 1), (0, True)) assert piecewise_fold(g1y.rewrite(Piecewise)) == \ Piecewise( (-1, y <= -1), (y**2/2 + y - S.Half, y <= 0), (-y**2/2 + y - S.Half, y < 1), (0, True)) assert gy1 == Piecewise( ( -Min(1, Max(-1, y))**2/2 - Min(1, Max(-1, y)) + Min(1, Max(0, y))**2 + S.Half, y < 1), (0, True) ) assert g1y == Piecewise( ( Min(1, Max(-1, y))**2/2 + Min(1, Max(-1, y)) - Min(1, Max(0, y))**2 - S.Half, y < 1), (0, True)) @slow def test_piecewise_integrate1cb(): y = symbols('y', real=True) g = Piecewise( (0, Or(x <= -1, x >= 1)), (1 - x, x > 0), (1 + x, True) ) gy1 = g.integrate((x, y, 1)) g1y = g.integrate((x, 1, y)) assert g.integrate((x, -2, 1)) == gy1.subs(y, -2) assert g.integrate((x, 1, -2)) == g1y.subs(y, -2) assert g.integrate((x, 0, 1)) == gy1.subs(y, 0) assert g.integrate((x, 1, 0)) == g1y.subs(y, 0) assert g.integrate((x, 2, 1)) == gy1.subs(y, 2) assert g.integrate((x, 1, 2)) == g1y.subs(y, 2) assert piecewise_fold(gy1.rewrite(Piecewise)) == \ Piecewise( (1, y <= -1), (-y**2/2 - y + S.Half, y <= 0), (y**2/2 - y + S.Half, y < 1), (0, True)) assert piecewise_fold(g1y.rewrite(Piecewise)) == \ Piecewise( (-1, y <= -1), (y**2/2 + y - S.Half, y <= 0), (-y**2/2 + y - S.Half, y < 1), (0, True)) # g1y and gy1 should simplify if the condition that y < 1 # is applied, e.g. Min(1, Max(-1, y)) --> Max(-1, y) assert gy1 == Piecewise( ( -Min(1, Max(-1, y))**2/2 - Min(1, Max(-1, y)) + Min(1, Max(0, y))**2 + S.Half, y < 1), (0, True) ) assert g1y == Piecewise( ( Min(1, Max(-1, y))**2/2 + Min(1, Max(-1, y)) - Min(1, Max(0, y))**2 - S.Half, y < 1), (0, True)) def test_piecewise_integrate2(): from itertools import permutations lim = Tuple(x, c, d) p = Piecewise((1, x < a), (2, x > b), (3, True)) q = p.integrate(lim) assert q == Piecewise( (-c + 2*d - 2*Min(d, Max(a, c)) + Min(d, Max(a, b, c)), c < d), (-2*c + d + 2*Min(c, Max(a, d)) - Min(c, Max(a, b, d)), True)) for v in permutations((1, 2, 3, 4)): r = dict(zip((a, b, c, d), v)) assert p.subs(r).integrate(lim.subs(r)) == q.subs(r) def test_meijer_bypass(): # totally bypass meijerg machinery when dealing # with Piecewise in integrate assert Piecewise((1, x < 4), (0, True)).integrate((x, oo, 1)) == -3 def test_piecewise_integrate3_inequality_conditions(): from sympy.utilities.iterables import cartes lim = (x, 0, 5) # set below includes two pts below range, 2 pts in range, # 2 pts above range, and the boundaries N = (-2, -1, 0, 1, 2, 5, 6, 7) p = Piecewise((1, x > a), (2, x > b), (0, True)) ans = p.integrate(lim) for i, j in cartes(N, repeat=2): reps = dict(zip((a, b), (i, j))) assert ans.subs(reps) == p.subs(reps).integrate(lim) assert ans.subs(a, 4).subs(b, 1) == 0 + 2*3 + 1 p = Piecewise((1, x > a), (2, x < b), (0, True)) ans = p.integrate(lim) for i, j in cartes(N, repeat=2): reps = dict(zip((a, b), (i, j))) assert ans.subs(reps) == p.subs(reps).integrate(lim) # delete old tests that involved c1 and c2 since those # reduce to the above except that a value of 0 was used # for two expressions whereas the above uses 3 different # values @slow def test_piecewise_integrate4_symbolic_conditions(): a = Symbol('a', real=True, finite=True) b = Symbol('b', real=True, finite=True) x = Symbol('x', real=True, finite=True) y = Symbol('y', real=True, finite=True) p0 = Piecewise((0, Or(x < a, x > b)), (1, True)) p1 = Piecewise((0, x < a), (0, x > b), (1, True)) p2 = Piecewise((0, x > b), (0, x < a), (1, True)) p3 = Piecewise((0, x < a), (1, x < b), (0, True)) p4 = Piecewise((0, x > b), (1, x > a), (0, True)) p5 = Piecewise((1, And(a < x, x < b)), (0, True)) # check values of a=1, b=3 (and reversed) with values # of y of 0, 1, 2, 3, 4 lim = Tuple(x, -oo, y) for p in (p0, p1, p2, p3, p4, p5): ans = p.integrate(lim) for i in range(5): reps = {a:1, b:3, y:i} assert ans.subs(reps) == p.subs(reps).integrate(lim.subs(reps)) reps = {a: 3, b:1, y:i} assert ans.subs(reps) == p.subs(reps).integrate(lim.subs(reps)) lim = Tuple(x, y, oo) for p in (p0, p1, p2, p3, p4, p5): ans = p.integrate(lim) for i in range(5): reps = {a:1, b:3, y:i} assert ans.subs(reps) == p.subs(reps).integrate(lim.subs(reps)) reps = {a:3, b:1, y:i} assert ans.subs(reps) == p.subs(reps).integrate(lim.subs(reps)) ans = Piecewise( (0, x <= Min(a, b)), (x - Min(a, b), x <= b), (b - Min(a, b), True)) for i in (p0, p1, p2, p4): assert i.integrate(x) == ans assert p3.integrate(x) == Piecewise( (0, x < a), (-a + x, x <= Max(a, b)), (-a + Max(a, b), True)) assert p5.integrate(x) == Piecewise( (0, x <= a), (-a + x, x <= Max(a, b)), (-a + Max(a, b), True)) p1 = Piecewise((0, x < a), (0.5, x > b), (1, True)) p2 = Piecewise((0.5, x > b), (0, x < a), (1, True)) p3 = Piecewise((0, x < a), (1, x < b), (0.5, True)) p4 = Piecewise((0.5, x > b), (1, x > a), (0, True)) p5 = Piecewise((1, And(a < x, x < b)), (0.5, x > b), (0, True)) # check values of a=1, b=3 (and reversed) with values # of y of 0, 1, 2, 3, 4 lim = Tuple(x, -oo, y) for p in (p1, p2, p3, p4, p5): ans = p.integrate(lim) for i in range(5): reps = {a:1, b:3, y:i} assert ans.subs(reps) == p.subs(reps).integrate(lim.subs(reps)) reps = {a: 3, b:1, y:i} assert ans.subs(reps) == p.subs(reps).integrate(lim.subs(reps)) def test_piecewise_integrate5_independent_conditions(): p = Piecewise((0, Eq(y, 0)), (x*y, True)) assert integrate(p, (x, 1, 3)) == Piecewise((0, Eq(y, 0)), (4*y, True)) def test_piecewise_simplify(): p = Piecewise(((x**2 + 1)/x**2, Eq(x*(1 + x) - x**2, 0)), ((-1)**x*(-1), True)) assert p.simplify() == \ Piecewise((zoo, Eq(x, 0)), ((-1)**(x + 1), True)) # simplify when there are Eq in conditions assert Piecewise( (a, And(Eq(a, 0), Eq(a + b, 0))), (1, True)).simplify( ) == Piecewise( (0, And(Eq(a, 0), Eq(b, 0))), (1, True)) assert Piecewise((2*x*factorial(a)/(factorial(y)*factorial(-y + a)), Eq(y, 0) & Eq(-y + a, 0)), (2*factorial(a)/(factorial(y)*factorial(-y + a)), Eq(y, 0) & Eq(-y + a, 1)), (0, True)).simplify( ) == Piecewise( (2*x, And(Eq(a, 0), Eq(y, 0))), (2, And(Eq(a, 1), Eq(y, 0))), (0, True)) args = (2, And(Eq(x, 2), Ge(y ,0))), (x, True) assert Piecewise(*args).simplify() == Piecewise(*args) args = (1, Eq(x, 0)), (sin(x)/x, True) assert Piecewise(*args).simplify() == Piecewise(*args) assert Piecewise((2 + y, And(Eq(x, 2), Eq(y, 0))), (x, True) ).simplify() == x # check that x or f(x) are recognized as being Symbol-like for lhs args = Tuple((1, Eq(x, 0)), (sin(x) + 1 + x, True)) ans = x + sin(x) + 1 f = Function('f') assert Piecewise(*args).simplify() == ans assert Piecewise(*args.subs(x, f(x))).simplify() == ans.subs(x, f(x)) # issue 18634 d = Symbol("d", integer=True) n = Symbol("n", integer=True) t = Symbol("t", real=True, positive=True) expr = Piecewise((-d + 2*n, Eq(1/t, 1)), (t**(1 - 4*n)*t**(4*n - 1)*(-d + 2*n), True)) assert expr.simplify() == -d + 2*n def test_piecewise_solve(): abs2 = Piecewise((-x, x <= 0), (x, x > 0)) f = abs2.subs(x, x - 2) assert solve(f, x) == [2] assert solve(f - 1, x) == [1, 3] f = Piecewise(((x - 2)**2, x >= 0), (1, True)) assert solve(f, x) == [2] g = Piecewise(((x - 5)**5, x >= 4), (f, True)) assert solve(g, x) == [2, 5] g = Piecewise(((x - 5)**5, x >= 4), (f, x < 4)) assert solve(g, x) == [2, 5] g = Piecewise(((x - 5)**5, x >= 2), (f, x < 2)) assert solve(g, x) == [5] g = Piecewise(((x - 5)**5, x >= 2), (f, True)) assert solve(g, x) == [5] g = Piecewise(((x - 5)**5, x >= 2), (f, True), (10, False)) assert solve(g, x) == [5] g = Piecewise(((x - 5)**5, x >= 2), (-x + 2, x - 2 <= 0), (x - 2, x - 2 > 0)) assert solve(g, x) == [5] # if no symbol is given the piecewise detection must still work assert solve(Piecewise((x - 2, x > 2), (2 - x, True)) - 3) == [-1, 5] f = Piecewise(((x - 2)**2, x >= 0), (0, True)) raises(NotImplementedError, lambda: solve(f, x)) def nona(ans): return list(filter(lambda x: x is not S.NaN, ans)) p = Piecewise((x**2 - 4, x < y), (x - 2, True)) ans = solve(p, x) assert nona([i.subs(y, -2) for i in ans]) == [2] assert nona([i.subs(y, 2) for i in ans]) == [-2, 2] assert nona([i.subs(y, 3) for i in ans]) == [-2, 2] assert ans == [ Piecewise((-2, y > -2), (S.NaN, True)), Piecewise((2, y <= 2), (S.NaN, True)), Piecewise((2, y > 2), (S.NaN, True))] # issue 6060 absxm3 = Piecewise( (x - 3, 0 <= x - 3), (3 - x, 0 > x - 3) ) assert solve(absxm3 - y, x) == [ Piecewise((-y + 3, -y < 0), (S.NaN, True)), Piecewise((y + 3, y >= 0), (S.NaN, True))] p = Symbol('p', positive=True) assert solve(absxm3 - p, x) == [-p + 3, p + 3] # issue 6989 f = Function('f') assert solve(Eq(-f(x), Piecewise((1, x > 0), (0, True))), f(x)) == \ [Piecewise((-1, x > 0), (0, True))] # issue 8587 f = Piecewise((2*x**2, And(0 < x, x < 1)), (2, True)) assert solve(f - 1) == [1/sqrt(2)] def test_piecewise_fold(): p = Piecewise((x, x < 1), (1, 1 <= x)) assert piecewise_fold(x*p) == Piecewise((x**2, x < 1), (x, 1 <= x)) assert piecewise_fold(p + p) == Piecewise((2*x, x < 1), (2, 1 <= x)) assert piecewise_fold(Piecewise((1, x < 0), (2, True)) + Piecewise((10, x < 0), (-10, True))) == \ Piecewise((11, x < 0), (-8, True)) p1 = Piecewise((0, x < 0), (x, x <= 1), (0, True)) p2 = Piecewise((0, x < 0), (1 - x, x <= 1), (0, True)) p = 4*p1 + 2*p2 assert integrate( piecewise_fold(p), (x, -oo, oo)) == integrate(2*x + 2, (x, 0, 1)) assert piecewise_fold( Piecewise((1, y <= 0), (-Piecewise((2, y >= 0)), True) )) == Piecewise((1, y <= 0), (-2, y >= 0)) assert piecewise_fold(Piecewise((x, ITE(x > 0, y < 1, y > 1))) ) == Piecewise((x, ((x <= 0) | (y < 1)) & ((x > 0) | (y > 1)))) a, b = (Piecewise((2, Eq(x, 0)), (0, True)), Piecewise((x, Eq(-x + y, 0)), (1, Eq(-x + y, 1)), (0, True))) assert piecewise_fold(Mul(a, b, evaluate=False) ) == piecewise_fold(Mul(b, a, evaluate=False)) def test_piecewise_fold_piecewise_in_cond(): p1 = Piecewise((cos(x), x < 0), (0, True)) p2 = Piecewise((0, Eq(p1, 0)), (p1 / Abs(p1), True)) assert p2.subs(x, -pi/2) == 0 assert p2.subs(x, 1) == 0 assert p2.subs(x, -pi/4) == 1 p4 = Piecewise((0, Eq(p1, 0)), (1,True)) ans = piecewise_fold(p4) for i in range(-1, 1): assert ans.subs(x, i) == p4.subs(x, i) r1 = 1 < Piecewise((1, x < 1), (3, True)) ans = piecewise_fold(r1) for i in range(2): assert ans.subs(x, i) == r1.subs(x, i) p5 = Piecewise((1, x < 0), (3, True)) p6 = Piecewise((1, x < 1), (3, True)) p7 = Piecewise((1, p5 < p6), (0, True)) ans = piecewise_fold(p7) for i in range(-1, 2): assert ans.subs(x, i) == p7.subs(x, i) def test_piecewise_fold_piecewise_in_cond_2(): p1 = Piecewise((cos(x), x < 0), (0, True)) p2 = Piecewise((0, Eq(p1, 0)), (1 / p1, True)) p3 = Piecewise( (0, (x >= 0) | Eq(cos(x), 0)), (1/cos(x), x < 0), (zoo, True)) # redundant b/c all x are already covered assert(piecewise_fold(p2) == p3) def test_piecewise_fold_expand(): p1 = Piecewise((1, Interval(0, 1, False, True).contains(x)), (0, True)) p2 = piecewise_fold(expand((1 - x)*p1)) assert p2 == Piecewise((1 - x, (x >= 0) & (x < 1)), (0, True)) assert p2 == expand(piecewise_fold((1 - x)*p1)) def test_piecewise_duplicate(): p = Piecewise((x, x < -10), (x**2, x <= -1), (x, 1 < x)) assert p == Piecewise(*p.args) def test_doit(): p1 = Piecewise((x, x < 1), (x**2, -1 <= x), (x, 3 < x)) p2 = Piecewise((x, x < 1), (Integral(2 * x), -1 <= x), (x, 3 < x)) assert p2.doit() == p1 assert p2.doit(deep=False) == p2 # issue 17165 p1 = Sum(y**x, (x, -1, oo)).doit() assert p1.doit() == p1 def test_piecewise_interval(): p1 = Piecewise((x, Interval(0, 1).contains(x)), (0, True)) assert p1.subs(x, -0.5) == 0 assert p1.subs(x, 0.5) == 0.5 assert p1.diff(x) == Piecewise((1, Interval(0, 1).contains(x)), (0, True)) assert integrate(p1, x) == Piecewise( (0, x <= 0), (x**2/2, x <= 1), (S.Half, True)) def test_piecewise_collapse(): assert Piecewise((x, True)) == x a = x < 1 assert Piecewise((x, a), (x + 1, a)) == Piecewise((x, a)) assert Piecewise((x, a), (x + 1, a.reversed)) == Piecewise((x, a)) b = x < 5 def canonical(i): if isinstance(i, Piecewise): return Piecewise(*i.args) return i for args in [ ((1, a), (Piecewise((2, a), (3, b)), b)), ((1, a), (Piecewise((2, a), (3, b.reversed)), b)), ((1, a), (Piecewise((2, a), (3, b)), b), (4, True)), ((1, a), (Piecewise((2, a), (3, b), (4, True)), b)), ((1, a), (Piecewise((2, a), (3, b), (4, True)), b), (5, True))]: for i in (0, 2, 10): assert canonical( Piecewise(*args, evaluate=False).subs(x, i) ) == canonical(Piecewise(*args).subs(x, i)) r1, r2, r3, r4 = symbols('r1:5') a = x < r1 b = x < r2 c = x < r3 d = x < r4 assert Piecewise((1, a), (Piecewise( (2, a), (3, b), (4, c)), b), (5, c) ) == Piecewise((1, a), (3, b), (5, c)) assert Piecewise((1, a), (Piecewise( (2, a), (3, b), (4, c), (6, True)), c), (5, d) ) == Piecewise((1, a), (Piecewise( (3, b), (4, c)), c), (5, d)) assert Piecewise((1, Or(a, d)), (Piecewise( (2, d), (3, b), (4, c)), b), (5, c) ) == Piecewise((1, Or(a, d)), (Piecewise( (2, d), (3, b)), b), (5, c)) assert Piecewise((1, c), (2, ~c), (3, S.true) ) == Piecewise((1, c), (2, S.true)) assert Piecewise((1, c), (2, And(~c, b)), (3,True) ) == Piecewise((1, c), (2, b), (3, True)) assert Piecewise((1, c), (2, Or(~c, b)), (3,True) ).subs(dict(zip((r1, r2, r3, r4, x), (1, 2, 3, 4, 3.5)))) == 2 assert Piecewise((1, c), (2, ~c)) == Piecewise((1, c), (2, True)) def test_piecewise_lambdify(): p = Piecewise( (x**2, x < 0), (x, Interval(0, 1, False, True).contains(x)), (2 - x, x >= 1), (0, True) ) f = lambdify(x, p) assert f(-2.0) == 4.0 assert f(0.0) == 0.0 assert f(0.5) == 0.5 assert f(2.0) == 0.0 def test_piecewise_series(): from sympy import sin, cos, O p1 = Piecewise((sin(x), x < 0), (cos(x), x > 0)) p2 = Piecewise((x + O(x**2), x < 0), (1 + O(x**2), x > 0)) assert p1.nseries(x, n=2) == p2 def test_piecewise_as_leading_term(): p1 = Piecewise((1/x, x > 1), (0, True)) p2 = Piecewise((x, x > 1), (0, True)) p3 = Piecewise((1/x, x > 1), (x, True)) p4 = Piecewise((x, x > 1), (1/x, True)) p5 = Piecewise((1/x, x > 1), (x, True)) p6 = Piecewise((1/x, x < 1), (x, True)) p7 = Piecewise((x, x < 1), (1/x, True)) p8 = Piecewise((x, x > 1), (1/x, True)) assert p1.as_leading_term(x) == 0 assert p2.as_leading_term(x) == 0 assert p3.as_leading_term(x) == x assert p4.as_leading_term(x) == 1/x assert p5.as_leading_term(x) == x assert p6.as_leading_term(x) == 1/x assert p7.as_leading_term(x) == x assert p8.as_leading_term(x) == 1/x def test_piecewise_complex(): p1 = Piecewise((2, x < 0), (1, 0 <= x)) p2 = Piecewise((2*I, x < 0), (I, 0 <= x)) p3 = Piecewise((I*x, x > 1), (1 + I, True)) p4 = Piecewise((-I*conjugate(x), x > 1), (1 - I, True)) assert conjugate(p1) == p1 assert conjugate(p2) == piecewise_fold(-p2) assert conjugate(p3) == p4 assert p1.is_imaginary is False assert p1.is_real is True assert p2.is_imaginary is True assert p2.is_real is False assert p3.is_imaginary is None assert p3.is_real is None assert p1.as_real_imag() == (p1, 0) assert p2.as_real_imag() == (0, -I*p2) def test_conjugate_transpose(): A, B = symbols("A B", commutative=False) p = Piecewise((A*B**2, x > 0), (A**2*B, True)) assert p.adjoint() == \ Piecewise((adjoint(A*B**2), x > 0), (adjoint(A**2*B), True)) assert p.conjugate() == \ Piecewise((conjugate(A*B**2), x > 0), (conjugate(A**2*B), True)) assert p.transpose() == \ Piecewise((transpose(A*B**2), x > 0), (transpose(A**2*B), True)) def test_piecewise_evaluate(): assert Piecewise((x, True)) == x assert Piecewise((x, True), evaluate=True) == x p = Piecewise((x, True), evaluate=False) assert p != x assert p.is_Piecewise assert all(isinstance(i, Basic) for i in p.args) assert Piecewise((1, Eq(1, x))).args == ((1, Eq(x, 1)),) assert Piecewise((1, Eq(1, x)), evaluate=False).args == ( (1, Eq(1, x)),) def test_as_expr_set_pairs(): assert Piecewise((x, x > 0), (-x, x <= 0)).as_expr_set_pairs() == \ [(x, Interval(0, oo, True, True)), (-x, Interval(-oo, 0))] assert Piecewise(((x - 2)**2, x >= 0), (0, True)).as_expr_set_pairs() == \ [((x - 2)**2, Interval(0, oo)), (0, Interval(-oo, 0, True, True))] def test_S_srepr_is_identity(): p = Piecewise((10, Eq(x, 0)), (12, True)) q = S(srepr(p)) assert p == q def test_issue_12587(): # sort holes into intervals p = Piecewise((1, x > 4), (2, Not((x <= 3) & (x > -1))), (3, True)) assert p.integrate((x, -5, 5)) == 23 p = Piecewise((1, x > 1), (2, x < y), (3, True)) lim = x, -3, 3 ans = p.integrate(lim) for i in range(-1, 3): assert ans.subs(y, i) == p.subs(y, i).integrate(lim) def test_issue_11045(): assert integrate(1/(x*sqrt(x**2 - 1)), (x, 1, 2)) == pi/3 # handle And with Or arguments assert Piecewise((1, And(Or(x < 1, x > 3), x < 2)), (0, True) ).integrate((x, 0, 3)) == 1 # hidden false assert Piecewise((1, x > 1), (2, x > x + 1), (3, True) ).integrate((x, 0, 3)) == 5 # targetcond is Eq assert Piecewise((1, x > 1), (2, Eq(1, x)), (3, True) ).integrate((x, 0, 4)) == 6 # And has Relational needing to be solved assert Piecewise((1, And(2*x > x + 1, x < 2)), (0, True) ).integrate((x, 0, 3)) == 1 # Or has Relational needing to be solved assert Piecewise((1, Or(2*x > x + 2, x < 1)), (0, True) ).integrate((x, 0, 3)) == 2 # ignore hidden false (handled in canonicalization) assert Piecewise((1, x > 1), (2, x > x + 1), (3, True) ).integrate((x, 0, 3)) == 5 # watch for hidden True Piecewise assert Piecewise((2, Eq(1 - x, x*(1/x - 1))), (0, True) ).integrate((x, 0, 3)) == 6 # overlapping conditions of targetcond are recognized and ignored; # the condition x > 3 will be pre-empted by the first condition assert Piecewise((1, Or(x < 1, x > 2)), (2, x > 3), (3, True) ).integrate((x, 0, 4)) == 6 # convert Ne to Or assert Piecewise((1, Ne(x, 0)), (2, True) ).integrate((x, -1, 1)) == 2 # no default but well defined assert Piecewise((x, (x > 1) & (x < 3)), (1, (x < 4)) ).integrate((x, 1, 4)) == 5 p = Piecewise((x, (x > 1) & (x < 3)), (1, (x < 4))) nan = Undefined i = p.integrate((x, 1, y)) assert i == Piecewise( (y - 1, y < 1), (Min(3, y)**2/2 - Min(3, y) + Min(4, y) - S.Half, y <= Min(4, y)), (nan, True)) assert p.integrate((x, 1, -1)) == i.subs(y, -1) assert p.integrate((x, 1, 4)) == 5 assert p.integrate((x, 1, 5)) is nan # handle Not p = Piecewise((1, x > 1), (2, Not(And(x > 1, x< 3))), (3, True)) assert p.integrate((x, 0, 3)) == 4 # handle updating of int_expr when there is overlap p = Piecewise( (1, And(5 > x, x > 1)), (2, Or(x < 3, x > 7)), (4, x < 8)) assert p.integrate((x, 0, 10)) == 20 # And with Eq arg handling assert Piecewise((1, x < 1), (2, And(Eq(x, 3), x > 1)) ).integrate((x, 0, 3)) is S.NaN assert Piecewise((1, x < 1), (2, And(Eq(x, 3), x > 1)), (3, True) ).integrate((x, 0, 3)) == 7 assert Piecewise((1, x < 0), (2, And(Eq(x, 3), x < 1)), (3, True) ).integrate((x, -1, 1)) == 4 # middle condition doesn't matter: it's a zero width interval assert Piecewise((1, x < 1), (2, Eq(x, 3) & (y < x)), (3, True) ).integrate((x, 0, 3)) == 7 def test_holes(): nan = Undefined assert Piecewise((1, x < 2)).integrate(x) == Piecewise( (x, x < 2), (nan, True)) assert Piecewise((1, And(x > 1, x < 2))).integrate(x) == Piecewise( (nan, x < 1), (x - 1, x < 2), (nan, True)) assert Piecewise((1, And(x > 1, x < 2))).integrate((x, 0, 3)) is nan assert Piecewise((1, And(x > 0, x < 4))).integrate((x, 1, 3)) == 2 # this also tests that the integrate method is used on non-Piecwise # arguments in _eval_integral A, B = symbols("A B") a, b = symbols('a b', real=True) assert Piecewise((A, And(x < 0, a < 1)), (B, Or(x < 1, a > 2)) ).integrate(x) == Piecewise( (B*x, (a > 2)), (Piecewise((A*x, x < 0), (B*x, x < 1), (nan, True)), a < 1), (Piecewise((B*x, x < 1), (nan, True)), True)) def test_issue_11922(): def f(x): return Piecewise((0, x < -1), (1 - x**2, x < 1), (0, True)) autocorr = lambda k: ( f(x) * f(x + k)).integrate((x, -1, 1)) assert autocorr(1.9) > 0 k = symbols('k') good_autocorr = lambda k: ( (1 - x**2) * f(x + k)).integrate((x, -1, 1)) a = good_autocorr(k) assert a.subs(k, 3) == 0 k = symbols('k', positive=True) a = good_autocorr(k) assert a.subs(k, 3) == 0 assert Piecewise((0, x < 1), (10, (x >= 1)) ).integrate() == Piecewise((0, x < 1), (10*x - 10, True)) def test_issue_5227(): f = 0.0032513612725229*Piecewise((0, x < -80.8461538461539), (-0.0160799238820171*x + 1.33215984776403, x < 2), (Piecewise((0.3, x > 123), (0.7, True)) + Piecewise((0.4, x > 2), (0.6, True)), x <= 123), (-0.00817409766454352*x + 2.10541401273885, x < 380.571428571429), (0, True)) i = integrate(f, (x, -oo, oo)) assert i == Integral(f, (x, -oo, oo)).doit() assert str(i) == '1.00195081676351' assert Piecewise((1, x - y < 0), (0, True) ).integrate(y) == Piecewise((0, y <= x), (-x + y, True)) def test_issue_10137(): a = Symbol('a', real=True, finite=True) b = Symbol('b', real=True, finite=True) x = Symbol('x', real=True, finite=True) y = Symbol('y', real=True, finite=True) p0 = Piecewise((0, Or(x < a, x > b)), (1, True)) p1 = Piecewise((0, Or(a > x, b < x)), (1, True)) assert integrate(p0, (x, y, oo)) == integrate(p1, (x, y, oo)) p3 = Piecewise((1, And(0 < x, x < a)), (0, True)) p4 = Piecewise((1, And(a > x, x > 0)), (0, True)) ip3 = integrate(p3, x) assert ip3 == Piecewise( (0, x <= 0), (x, x <= Max(0, a)), (Max(0, a), True)) ip4 = integrate(p4, x) assert ip4 == ip3 assert p3.integrate((x, 2, 4)) == Min(4, Max(2, a)) - 2 assert p4.integrate((x, 2, 4)) == Min(4, Max(2, a)) - 2 def test_stackoverflow_43852159(): f = lambda x: Piecewise((1 , (x >= -1) & (x <= 1)) , (0, True)) Conv = lambda x: integrate(f(x - y)*f(y), (y, -oo, +oo)) cx = Conv(x) assert cx.subs(x, -1.5) == cx.subs(x, 1.5) assert cx.subs(x, 3) == 0 assert piecewise_fold(f(x - y)*f(y)) == Piecewise( (1, (y >= -1) & (y <= 1) & (x - y >= -1) & (x - y <= 1)), (0, True)) def test_issue_12557(): ''' # 3200 seconds to compute the fourier part of issue import sympy as sym x,y,z,t = sym.symbols('x y z t') k = sym.symbols("k", integer=True) fourier = sym.fourier_series(sym.cos(k*x)*sym.sqrt(x**2), (x, -sym.pi, sym.pi)) assert fourier == FourierSeries( sqrt(x**2)*cos(k*x), (x, -pi, pi), (Piecewise((pi**2, Eq(k, 0)), (2*(-1)**k/k**2 - 2/k**2, True))/(2*pi), SeqFormula(Piecewise((pi**2, (Eq(_n, 0) & Eq(k, 0)) | (Eq(_n, 0) & Eq(_n, k) & Eq(k, 0)) | (Eq(_n, 0) & Eq(k, 0) & Eq(_n, -k)) | (Eq(_n, 0) & Eq(_n, k) & Eq(k, 0) & Eq(_n, -k))), (pi**2/2, Eq(_n, k) | Eq(_n, -k) | (Eq(_n, 0) & Eq(_n, k)) | (Eq(_n, k) & Eq(k, 0)) | (Eq(_n, 0) & Eq(_n, -k)) | (Eq(_n, k) & Eq(_n, -k)) | (Eq(k, 0) & Eq(_n, -k)) | (Eq(_n, 0) & Eq(_n, k) & Eq(_n, -k)) | (Eq(_n, k) & Eq(k, 0) & Eq(_n, -k))), ((-1)**k*pi**2*_n**3*sin(pi*_n)/(pi*_n**4 - 2*pi*_n**2*k**2 + pi*k**4) - (-1)**k*pi**2*_n**3*sin(pi*_n)/(-pi*_n**4 + 2*pi*_n**2*k**2 - pi*k**4) + (-1)**k*pi*_n**2*cos(pi*_n)/(pi*_n**4 - 2*pi*_n**2*k**2 + pi*k**4) - (-1)**k*pi*_n**2*cos(pi*_n)/(-pi*_n**4 + 2*pi*_n**2*k**2 - pi*k**4) - (-1)**k*pi**2*_n*k**2*sin(pi*_n)/(pi*_n**4 - 2*pi*_n**2*k**2 + pi*k**4) + (-1)**k*pi**2*_n*k**2*sin(pi*_n)/(-pi*_n**4 + 2*pi*_n**2*k**2 - pi*k**4) + (-1)**k*pi*k**2*cos(pi*_n)/(pi*_n**4 - 2*pi*_n**2*k**2 + pi*k**4) - (-1)**k*pi*k**2*cos(pi*_n)/(-pi*_n**4 + 2*pi*_n**2*k**2 - pi*k**4) - (2*_n**2 + 2*k**2)/(_n**4 - 2*_n**2*k**2 + k**4), True))*cos(_n*x)/pi, (_n, 1, oo)), SeqFormula(0, (_k, 1, oo)))) ''' x = symbols("x", real=True) k = symbols('k', integer=True, finite=True) abs2 = lambda x: Piecewise((-x, x <= 0), (x, x > 0)) assert integrate(abs2(x), (x, -pi, pi)) == pi**2 func = cos(k*x)*sqrt(x**2) assert integrate(func, (x, -pi, pi)) == Piecewise( (2*(-1)**k/k**2 - 2/k**2, Ne(k, 0)), (pi**2, True)) def test_issue_6900(): from itertools import permutations t0, t1, T, t = symbols('t0, t1 T t') f = Piecewise((0, t < t0), (x, And(t0 <= t, t < t1)), (0, t >= t1)) g = f.integrate(t) assert g == Piecewise( (0, t <= t0), (t*x - t0*x, t <= Max(t0, t1)), (-t0*x + x*Max(t0, t1), True)) for i in permutations(range(2)): reps = dict(zip((t0,t1), i)) for tt in range(-1,3): assert (g.xreplace(reps).subs(t,tt) == f.xreplace(reps).integrate(t).subs(t,tt)) lim = Tuple(t, t0, T) g = f.integrate(lim) ans = Piecewise( (-t0*x + x*Min(T, Max(t0, t1)), T > t0), (0, True)) for i in permutations(range(3)): reps = dict(zip((t0,t1,T), i)) tru = f.xreplace(reps).integrate(lim.xreplace(reps)) assert tru == ans.xreplace(reps) assert g == ans def test_issue_10122(): assert solve(abs(x) + abs(x - 1) - 1 > 0, x ) == Or(And(-oo < x, x < S.Zero), And(S.One < x, x < oo)) def test_issue_4313(): u = Piecewise((0, x <= 0), (1, x >= a), (x/a, True)) e = (u - u.subs(x, y))**2/(x - y)**2 M = Max(0, a) assert integrate(e, x).expand() == Piecewise( (Piecewise( (0, x <= 0), (-y**2/(a**2*x - a**2*y) + x/a**2 - 2*y*log(-y)/a**2 + 2*y*log(x - y)/a**2 - y/a**2, x <= M), (-y**2/(-a**2*y + a**2*M) + 1/(-y + M) - 1/(x - y) - 2*y*log(-y)/a**2 + 2*y*log(-y + M)/a**2 - y/a**2 + M/a**2, True)), ((a <= y) & (y <= 0)) | ((y <= 0) & (y > -oo))), (Piecewise( (-1/(x - y), x <= 0), (-a**2/(a**2*x - a**2*y) + 2*a*y/(a**2*x - a**2*y) - y**2/(a**2*x - a**2*y) + 2*log(-y)/a - 2*log(x - y)/a + 2/a + x/a**2 - 2*y*log(-y)/a**2 + 2*y*log(x - y)/a**2 - y/a**2, x <= M), (-a**2/(-a**2*y + a**2*M) + 2*a*y/(-a**2*y + a**2*M) - y**2/(-a**2*y + a**2*M) + 2*log(-y)/a - 2*log(-y + M)/a + 2/a - 2*y*log(-y)/a**2 + 2*y*log(-y + M)/a**2 - y/a**2 + M/a**2, True)), a <= y), (Piecewise( (-y**2/(a**2*x - a**2*y), x <= 0), (x/a**2 + y/a**2, x <= M), (a**2/(-a**2*y + a**2*M) - a**2/(a**2*x - a**2*y) - 2*a*y/(-a**2*y + a**2*M) + 2*a*y/(a**2*x - a**2*y) + y**2/(-a**2*y + a**2*M) - y**2/(a**2*x - a**2*y) + y/a**2 + M/a**2, True)), True)) def test__intervals(): assert Piecewise((x + 2, Eq(x, 3)))._intervals(x) == [] assert Piecewise( (1, x > x + 1), (Piecewise((1, x < x + 1)), 2*x < 2*x + 1), (1, True))._intervals(x) == [(-oo, oo, 1, 1)] assert Piecewise((1, Ne(x, I)), (0, True))._intervals(x) == [ (-oo, oo, 1, 0)] assert Piecewise((-cos(x), sin(x) >= 0), (cos(x), True) )._intervals(x) == [(0, pi, -cos(x), 0), (-oo, oo, cos(x), 1)] # the following tests that duplicates are removed and that non-Eq # generated zero-width intervals are removed assert Piecewise((1, Abs(x**(-2)) > 1), (0, True) )._intervals(x) == [(-1, 0, 1, 0), (0, 1, 1, 0), (-oo, oo, 0, 1)] def test_containment(): a, b, c, d, e = [1, 2, 3, 4, 5] p = (Piecewise((d, x > 1), (e, True))* Piecewise((a, Abs(x - 1) < 1), (b, Abs(x - 2) < 2), (c, True))) assert p.integrate(x).diff(x) == Piecewise( (c*e, x <= 0), (a*e, x <= 1), (a*d, x < 2), # this is what we want to get right (b*d, x < 4), (c*d, True)) def test_piecewise_with_DiracDelta(): d1 = DiracDelta(x - 1) assert integrate(d1, (x, -oo, oo)) == 1 assert integrate(d1, (x, 0, 2)) == 1 assert Piecewise((d1, Eq(x, 2)), (0, True)).integrate(x) == 0 assert Piecewise((d1, x < 2), (0, True)).integrate(x) == Piecewise( (Heaviside(x - 1), x < 2), (1, True)) # TODO raise error if function is discontinuous at limit of # integration, e.g. integrate(d1, (x, -2, 1)) or Piecewise( # (d1, Eq(x ,1) def test_issue_10258(): assert Piecewise((0, x < 1), (1, True)).is_zero is None assert Piecewise((-1, x < 1), (1, True)).is_zero is False a = Symbol('a', zero=True) assert Piecewise((0, x < 1), (a, True)).is_zero assert Piecewise((1, x < 1), (a, x < 3)).is_zero is None a = Symbol('a') assert Piecewise((0, x < 1), (a, True)).is_zero is None assert Piecewise((0, x < 1), (1, True)).is_nonzero is None assert Piecewise((1, x < 1), (2, True)).is_nonzero assert Piecewise((0, x < 1), (oo, True)).is_finite is None assert Piecewise((0, x < 1), (1, True)).is_finite b = Basic() assert Piecewise((b, x < 1)).is_finite is None # 10258 c = Piecewise((1, x < 0), (2, True)) < 3 assert c != True assert piecewise_fold(c) == True def test_issue_10087(): a, b = Piecewise((x, x > 1), (2, True)), Piecewise((x, x > 3), (3, True)) m = a*b f = piecewise_fold(m) for i in (0, 2, 4): assert m.subs(x, i) == f.subs(x, i) m = a + b f = piecewise_fold(m) for i in (0, 2, 4): assert m.subs(x, i) == f.subs(x, i) def test_issue_8919(): c = symbols('c:5') x = symbols("x") f1 = Piecewise((c[1], x < 1), (c[2], True)) f2 = Piecewise((c[3], x < Rational(1, 3)), (c[4], True)) assert integrate(f1*f2, (x, 0, 2) ) == c[1]*c[3]/3 + 2*c[1]*c[4]/3 + c[2]*c[4] f1 = Piecewise((0, x < 1), (2, True)) f2 = Piecewise((3, x < 2), (0, True)) assert integrate(f1*f2, (x, 0, 3)) == 6 y = symbols("y", positive=True) a, b, c, x, z = symbols("a,b,c,x,z", real=True) I = Integral(Piecewise( (0, (x >= y) | (x < 0) | (b > c)), (a, True)), (x, 0, z)) ans = I.doit() assert ans == Piecewise((0, b > c), (a*Min(y, z) - a*Min(0, z), True)) for cond in (True, False): for yy in range(1, 3): for zz in range(-yy, 0, yy): reps = [(b > c, cond), (y, yy), (z, zz)] assert ans.subs(reps) == I.subs(reps).doit() def test_unevaluated_integrals(): f = Function('f') p = Piecewise((1, Eq(f(x) - 1, 0)), (2, x - 10 < 0), (0, True)) assert p.integrate(x) == Integral(p, x) assert p.integrate((x, 0, 5)) == Integral(p, (x, 0, 5)) # test it by replacing f(x) with x%2 which will not # affect the answer: the integrand is essentially 2 over # the domain of integration assert Integral(p, (x, 0, 5)).subs(f(x), x%2).n() == 10 # this is a test of using _solve_inequality when # solve_univariate_inequality fails assert p.integrate(y) == Piecewise( (y, Eq(f(x), 1) | ((x < 10) & Eq(f(x), 1))), (2*y, (x >= -oo) & (x < 10)), (0, True)) def test_conditions_as_alternate_booleans(): a, b, c = symbols('a:c') assert Piecewise((x, Piecewise((y < 1, x > 0), (y > 1, True))) ) == Piecewise((x, ITE(x > 0, y < 1, y > 1))) def test_Piecewise_rewrite_as_ITE(): a, b, c, d = symbols('a:d') def _ITE(*args): return Piecewise(*args).rewrite(ITE) assert _ITE((a, x < 1), (b, x >= 1)) == ITE(x < 1, a, b) assert _ITE((a, x < 1), (b, x < oo)) == ITE(x < 1, a, b) assert _ITE((a, x < 1), (b, Or(y < 1, x < oo)), (c, y > 0) ) == ITE(x < 1, a, b) assert _ITE((a, x < 1), (b, True)) == ITE(x < 1, a, b) assert _ITE((a, x < 1), (b, x < 2), (c, True) ) == ITE(x < 1, a, ITE(x < 2, b, c)) assert _ITE((a, x < 1), (b, y < 2), (c, True) ) == ITE(x < 1, a, ITE(y < 2, b, c)) assert _ITE((a, x < 1), (b, x < oo), (c, y < 1) ) == ITE(x < 1, a, b) assert _ITE((a, x < 1), (c, y < 1), (b, x < oo), (d, True) ) == ITE(x < 1, a, ITE(y < 1, c, b)) assert _ITE((a, x < 0), (b, Or(x < oo, y < 1)) ) == ITE(x < 0, a, b) raises(TypeError, lambda: _ITE((x + 1, x < 1), (x, True))) # if `a` in the following were replaced with y then the coverage # is complete but something other than as_set would need to be # used to detect this raises(NotImplementedError, lambda: _ITE((x, x < y), (y, x >= a))) raises(ValueError, lambda: _ITE((a, x < 2), (b, x > 3))) def test_issue_14052(): assert integrate(abs(sin(x)), (x, 0, 2*pi)) == 4 def test_issue_14240(): assert piecewise_fold( Piecewise((1, a), (2, b), (4, True)) + Piecewise((8, a), (16, True)) ) == Piecewise((9, a), (18, b), (20, True)) assert piecewise_fold( Piecewise((2, a), (3, b), (5, True)) * Piecewise((7, a), (11, True)) ) == Piecewise((14, a), (33, b), (55, True)) # these will hang if naive folding is used assert piecewise_fold(Add(*[ Piecewise((i, a), (0, True)) for i in range(40)]) ) == Piecewise((780, a), (0, True)) assert piecewise_fold(Mul(*[ Piecewise((i, a), (0, True)) for i in range(1, 41)]) ) == Piecewise((factorial(40), a), (0, True)) def test_issue_14787(): x = Symbol('x') f = Piecewise((x, x < 1), ((S(58) / 7), True)) assert str(f.evalf()) == "Piecewise((x, x < 1), (8.28571428571429, True))" def test_issue_8458(): x, y = symbols('x y') # Original issue p1 = Piecewise((0, Eq(x, 0)), (sin(x), True)) assert p1.simplify() == sin(x) # Slightly larger variant p2 = Piecewise((x, Eq(x, 0)), (4*x + (y-2)**4, Eq(x, 0) & Eq(x+y, 2)), (sin(x), True)) assert p2.simplify() == sin(x) # Test for problem highlighted during review p3 = Piecewise((x+1, Eq(x, -1)), (4*x + (y-2)**4, Eq(x, 0) & Eq(x+y, 2)), (sin(x), True)) assert p3.simplify() == Piecewise((0, Eq(x, -1)), (sin(x), True)) def test_issue_16417(): from sympy import im, re, Gt z = Symbol('z') assert unchanged(Piecewise, (1, Or(Eq(im(z), 0), Gt(re(z), 0))), (2, True)) x = Symbol('x') assert unchanged(Piecewise, (S.Pi, re(x) < 0), (0, Or(re(x) > 0, Ne(im(x), 0))), (S.NaN, True)) r = Symbol('r', real=True) p = Piecewise((S.Pi, re(r) < 0), (0, Or(re(r) > 0, Ne(im(r), 0))), (S.NaN, True)) assert p == Piecewise((S.Pi, r < 0), (0, r > 0), (S.NaN, True), evaluate=False) # Does not work since imaginary != 0... #i = Symbol('i', imaginary=True) #p = Piecewise((S.Pi, re(i) < 0), # (0, Or(re(i) > 0, Ne(im(i), 0))), # (S.NaN, True)) #assert p == Piecewise((0, Ne(im(i), 0)), # (S.NaN, True), evaluate=False) i = I*r p = Piecewise((S.Pi, re(i) < 0), (0, Or(re(i) > 0, Ne(im(i), 0))), (S.NaN, True)) assert p == Piecewise((0, Ne(im(i), 0)), (S.NaN, True), evaluate=False) assert p == Piecewise((0, Ne(r, 0)), (S.NaN, True), evaluate=False) def test_eval_rewrite_as_KroneckerDelta(): x, y, z, n, t, m = symbols('x y z n t m') K = KroneckerDelta f = lambda p: expand(p.rewrite(K)) p1 = Piecewise((0, Eq(x, y)), (1, True)) assert f(p1) == 1 - K(x, y) p2 = Piecewise((x, Eq(y,0)), (z, Eq(t,0)), (n, True)) assert f(p2) == n*K(0, t)*K(0, y) - n*K(0, t) - n*K(0, y) + n + \ x*K(0, y) - z*K(0, t)*K(0, y) + z*K(0, t) p3 = Piecewise((1, Ne(x, y)), (0, True)) assert f(p3) == 1 - K(x, y) p4 = Piecewise((1, Eq(x, 3)), (4, True), (5, True)) assert f(p4) == 4 - 3*K(3, x) p5 = Piecewise((3, Ne(x, 2)), (4, Eq(y, 2)), (5, True)) assert f(p5) == -K(2, x)*K(2, y) + 2*K(2, x) + 3 p6 = Piecewise((0, Ne(x, 1) & Ne(y, 4)), (1, True)) assert f(p6) == -K(1, x)*K(4, y) + K(1, x) + K(4, y) p7 = Piecewise((2, Eq(y, 3) & Ne(x, 2)), (1, True)) assert f(p7) == -K(2, x)*K(3, y) + K(3, y) + 1 p8 = Piecewise((4, Eq(x, 3) & Ne(y, 2)), (1, True)) assert f(p8) == -3*K(2, y)*K(3, x) + 3*K(3, x) + 1 p9 = Piecewise((6, Eq(x, 4) & Eq(y, 1)), (1, True)) assert f(p9) == 5 * K(1, y) * K(4, x) + 1 p10 = Piecewise((4, Ne(x, -4) | Ne(y, 1)), (1, True)) assert f(p10) == -3 * K(-4, x) * K(1, y) + 4 p11 = Piecewise((1, Eq(y, 2) | Ne(x, -3)), (2, True)) assert f(p11) == -K(-3, x)*K(2, y) + K(-3, x) + 1 p12 = Piecewise((-1, Eq(x, 1) | Ne(y, 3)), (1, True)) assert f(p12) == -2*K(1, x)*K(3, y) + 2*K(3, y) - 1 p13 = Piecewise((3, Eq(x, 2) | Eq(y, 4)), (1, True)) assert f(p13) == -2*K(2, x)*K(4, y) + 2*K(2, x) + 2*K(4, y) + 1 p14 = Piecewise((1, Ne(x, 0) | Ne(y, 1)), (3, True)) assert f(p14) == 2 * K(0, x) * K(1, y) + 1 p15 = Piecewise((2, Eq(x, 3) | Ne(y, 2)), (3, Eq(x, 4) & Eq(y, 5)), (1, True)) assert f(p15) == -2*K(2, y)*K(3, x)*K(4, x)*K(5, y) + K(2, y)*K(3, x) + \ 2*K(2, y)*K(4, x)*K(5, y) - K(2, y) + 2 p16 = Piecewise((0, Ne(m, n)), (1, True))*Piecewise((0, Ne(n, t)), (1, True))\ *Piecewise((0, Ne(n, x)), (1, True)) - Piecewise((0, Ne(t, x)), (1, True)) assert f(p16) == K(m, n)*K(n, t)*K(n, x) - K(t, x) p17 = Piecewise((0, Ne(t, x) & (Ne(m, n) | Ne(n, t) | Ne(n, x))), (1, Ne(t, x)), (-1, Ne(m, n) | Ne(n, t) | Ne(n, x)), (0, True)) assert f(p17) == K(m, n)*K(n, t)*K(n, x) - K(t, x) p18 = Piecewise((-4, Eq(y, 1) | (Eq(x, -5) & Eq(x, z))), (4, True)) assert f(p18) == 8*K(-5, x)*K(1, y)*K(x, z) - 8*K(-5, x)*K(x, z) - 8*K(1, y) + 4 p19 = Piecewise((0, x > 2), (1, True)) assert f(p19) == p19 p20 = Piecewise((0, And(x < 2, x > -5)), (1, True)) assert f(p20) == p20 p21 = Piecewise((0, Or(x > 1, x < 0)), (1, True)) assert f(p21) == p21 p22 = Piecewise((0, ~((Eq(y, -1) | Ne(x, 0)) & (Ne(x, 1) | Ne(y, -1)))), (1, True)) assert f(p22) == K(-1, y)*K(0, x) - K(-1, y)*K(1, x) - K(0, x) + 1 @slow def test_identical_conds_issue(): from sympy.stats import Uniform, density u1 = Uniform('u1', 0, 1) u2 = Uniform('u2', 0, 1) # Result is quite big, so not really important here (and should ideally be # simpler). Should not give an exception though. density(u1 + u2) def test_issue_7370(): f = Piecewise((1, x <= 2400)) v = integrate(f, (x, 0, Float("252.4", 30))) assert str(v) == '252.400000000000000000000000000' def test_issue_16715(): raises(NotImplementedError, lambda: Piecewise((x, x<0), (0, y>1)).as_expr_set_pairs()) def test_issue_20360(): t, tau = symbols("t tau", real=True) n = symbols("n", integer=True) lam = pi * (n - S.Half) eq = integrate(exp(lam * tau), (tau, 0, t)) assert simplify(eq) == (2*exp(pi*t*(2*n - 1)/2) - 2)/(pi*(2*n - 1))