from sympy.core.numbers import (E, I, Rational, oo, pi) from sympy.core.singleton import S from sympy.core.symbol import (Symbol, symbols) from sympy.functions.elementary.complexes import (Abs, re) from sympy.functions.elementary.exponential import (exp, log) from sympy.functions.elementary.miscellaneous import sqrt from sympy.functions.elementary.piecewise import Piecewise from sympy.functions.elementary.trigonometric import (cos, cot, csc, sec, sin, tan) from sympy.functions.special.error_functions import expint from sympy.matrices.expressions.matexpr import MatrixSymbol from sympy.simplify.simplify import simplify from sympy.calculus.util import (function_range, continuous_domain, not_empty_in, periodicity, lcim, is_convex, stationary_points, minimum, maximum) from sympy.sets.sets import (Interval, FiniteSet, Complement, Union) from sympy.testing.pytest import raises, _both_exp_pow from sympy.abc import x a = Symbol('a', real=True) def test_function_range(): x, y, a, b = symbols('x y a b') assert function_range(sin(x), x, Interval(-pi/2, pi/2) ) == Interval(-1, 1) assert function_range(sin(x), x, Interval(0, pi) ) == Interval(0, 1) assert function_range(tan(x), x, Interval(0, pi) ) == Interval(-oo, oo) assert function_range(tan(x), x, Interval(pi/2, pi) ) == Interval(-oo, 0) assert function_range((x + 3)/(x - 2), x, Interval(-5, 5) ) == Union(Interval(-oo, Rational(2, 7)), Interval(Rational(8, 3), oo)) assert function_range(1/(x**2), x, Interval(-1, 1) ) == Interval(1, oo) assert function_range(exp(x), x, Interval(-1, 1) ) == Interval(exp(-1), exp(1)) assert function_range(log(x) - x, x, S.Reals ) == Interval(-oo, -1) assert function_range(sqrt(3*x - 1), x, Interval(0, 2) ) == Interval(0, sqrt(5)) assert function_range(x*(x - 1) - (x**2 - x), x, S.Reals ) == FiniteSet(0) assert function_range(x*(x - 1) - (x**2 - x) + y, x, S.Reals ) == FiniteSet(y) assert function_range(sin(x), x, Union(Interval(-5, -3), FiniteSet(4)) ) == Union(Interval(-sin(3), 1), FiniteSet(sin(4))) assert function_range(cos(x), x, Interval(-oo, -4) ) == Interval(-1, 1) assert function_range(cos(x), x, S.EmptySet) == S.EmptySet assert function_range(x/sqrt(x**2+1), x, S.Reals) == Interval.open(-1,1) raises(NotImplementedError, lambda : function_range( exp(x)*(sin(x) - cos(x))/2 - x, x, S.Reals)) raises(NotImplementedError, lambda : function_range( sin(x) + x, x, S.Reals)) # issue 13273 raises(NotImplementedError, lambda : function_range( log(x), x, S.Integers)) raises(NotImplementedError, lambda : function_range( sin(x)/2, x, S.Naturals)) def test_continuous_domain(): x = Symbol('x') assert continuous_domain(sin(x), x, Interval(0, 2*pi)) == Interval(0, 2*pi) assert continuous_domain(tan(x), x, Interval(0, 2*pi)) == \ Union(Interval(0, pi/2, False, True), Interval(pi/2, pi*Rational(3, 2), True, True), Interval(pi*Rational(3, 2), 2*pi, True, False)) assert continuous_domain((x - 1)/((x - 1)**2), x, S.Reals) == \ Union(Interval(-oo, 1, True, True), Interval(1, oo, True, True)) assert continuous_domain(log(x) + log(4*x - 1), x, S.Reals) == \ Interval(Rational(1, 4), oo, True, True) assert continuous_domain(1/sqrt(x - 3), x, S.Reals) == Interval(3, oo, True, True) assert continuous_domain(1/x - 2, x, S.Reals) == \ Union(Interval.open(-oo, 0), Interval.open(0, oo)) assert continuous_domain(1/(x**2 - 4) + 2, x, S.Reals) == \ Union(Interval.open(-oo, -2), Interval.open(-2, 2), Interval.open(2, oo)) domain = continuous_domain(log(tan(x)**2 + 1), x, S.Reals) assert not domain.contains(3*pi/2) assert domain.contains(5) d = Symbol('d', even=True, zero=False) assert continuous_domain(x**(1/d), x, S.Reals) == Interval(0, oo) def test_not_empty_in(): assert not_empty_in(FiniteSet(x, 2*x).intersect(Interval(1, 2, True, False)), x) == \ Interval(S.Half, 2, True, False) assert not_empty_in(FiniteSet(x, x**2).intersect(Interval(1, 2)), x) == \ Union(Interval(-sqrt(2), -1), Interval(1, 2)) assert not_empty_in(FiniteSet(x**2 + x, x).intersect(Interval(2, 4)), x) == \ Union(Interval(-sqrt(17)/2 - S.Half, -2), Interval(1, Rational(-1, 2) + sqrt(17)/2), Interval(2, 4)) assert not_empty_in(FiniteSet(x/(x - 1)).intersect(S.Reals), x) == \ Complement(S.Reals, FiniteSet(1)) assert not_empty_in(FiniteSet(a/(a - 1)).intersect(S.Reals), a) == \ Complement(S.Reals, FiniteSet(1)) assert not_empty_in(FiniteSet((x**2 - 3*x + 2)/(x - 1)).intersect(S.Reals), x) == \ Complement(S.Reals, FiniteSet(1)) assert not_empty_in(FiniteSet(3, 4, x/(x - 1)).intersect(Interval(2, 3)), x) == \ Interval(-oo, oo) assert not_empty_in(FiniteSet(4, x/(x - 1)).intersect(Interval(2, 3)), x) == \ Interval(S(3)/2, 2) assert not_empty_in(FiniteSet(x/(x**2 - 1)).intersect(S.Reals), x) == \ Complement(S.Reals, FiniteSet(-1, 1)) assert not_empty_in(FiniteSet(x, x**2).intersect(Union(Interval(1, 3, True, True), Interval(4, 5))), x) == \ Union(Interval(-sqrt(5), -2), Interval(-sqrt(3), -1, True, True), Interval(1, 3, True, True), Interval(4, 5)) assert not_empty_in(FiniteSet(1).intersect(Interval(3, 4)), x) == S.EmptySet assert not_empty_in(FiniteSet(x**2/(x + 2)).intersect(Interval(1, oo)), x) == \ Union(Interval(-2, -1, True, False), Interval(2, oo)) raises(ValueError, lambda: not_empty_in(x)) raises(ValueError, lambda: not_empty_in(Interval(0, 1), x)) raises(NotImplementedError, lambda: not_empty_in(FiniteSet(x).intersect(S.Reals), x, a)) @_both_exp_pow def test_periodicity(): x = Symbol('x') y = Symbol('y') z = Symbol('z', real=True) assert periodicity(sin(2*x), x) == pi assert periodicity((-2)*tan(4*x), x) == pi/4 assert periodicity(sin(x)**2, x) == 2*pi assert periodicity(3**tan(3*x), x) == pi/3 assert periodicity(tan(x)*cos(x), x) == 2*pi assert periodicity(sin(x)**(tan(x)), x) == 2*pi assert periodicity(tan(x)*sec(x), x) == 2*pi assert periodicity(sin(2*x)*cos(2*x) - y, x) == pi/2 assert periodicity(tan(x) + cot(x), x) == pi assert periodicity(sin(x) - cos(2*x), x) == 2*pi assert periodicity(sin(x) - 1, x) == 2*pi assert periodicity(sin(4*x) + sin(x)*cos(x), x) == pi assert periodicity(exp(sin(x)), x) == 2*pi assert periodicity(log(cot(2*x)) - sin(cos(2*x)), x) == pi assert periodicity(sin(2*x)*exp(tan(x) - csc(2*x)), x) == pi assert periodicity(cos(sec(x) - csc(2*x)), x) == 2*pi assert periodicity(tan(sin(2*x)), x) == pi assert periodicity(2*tan(x)**2, x) == pi assert periodicity(sin(x%4), x) == 4 assert periodicity(sin(x)%4, x) == 2*pi assert periodicity(tan((3*x-2)%4), x) == Rational(4, 3) assert periodicity((sqrt(2)*(x+1)+x) % 3, x) == 3 / (sqrt(2)+1) assert periodicity((x**2+1) % x, x) is None assert periodicity(sin(re(x)), x) == 2*pi assert periodicity(sin(x)**2 + cos(x)**2, x) is S.Zero assert periodicity(tan(x), y) is S.Zero assert periodicity(sin(x) + I*cos(x), x) == 2*pi assert periodicity(x - sin(2*y), y) == pi assert periodicity(exp(x), x) is None assert periodicity(exp(I*x), x) == 2*pi assert periodicity(exp(I*z), z) == 2*pi assert periodicity(exp(z), z) is None assert periodicity(exp(log(sin(z) + I*cos(2*z)), evaluate=False), z) == 2*pi assert periodicity(exp(log(sin(2*z) + I*cos(z)), evaluate=False), z) == 2*pi assert periodicity(exp(sin(z)), z) == 2*pi assert periodicity(exp(2*I*z), z) == pi assert periodicity(exp(z + I*sin(z)), z) is None assert periodicity(exp(cos(z/2) + sin(z)), z) == 4*pi assert periodicity(log(x), x) is None assert periodicity(exp(x)**sin(x), x) is None assert periodicity(sin(x)**y, y) is None assert periodicity(Abs(sin(Abs(sin(x)))), x) == pi assert all(periodicity(Abs(f(x)), x) == pi for f in ( cos, sin, sec, csc, tan, cot)) assert periodicity(Abs(sin(tan(x))), x) == pi assert periodicity(Abs(sin(sin(x) + tan(x))), x) == 2*pi assert periodicity(sin(x) > S.Half, x) == 2*pi assert periodicity(x > 2, x) is None assert periodicity(x**3 - x**2 + 1, x) is None assert periodicity(Abs(x), x) is None assert periodicity(Abs(x**2 - 1), x) is None assert periodicity((x**2 + 4)%2, x) is None assert periodicity((E**x)%3, x) is None assert periodicity(sin(expint(1, x))/expint(1, x), x) is None # returning `None` for any Piecewise p = Piecewise((0, x < -1), (x**2, x <= 1), (log(x), True)) assert periodicity(p, x) is None m = MatrixSymbol('m', 3, 3) raises(NotImplementedError, lambda: periodicity(sin(m), m)) raises(NotImplementedError, lambda: periodicity(sin(m[0, 0]), m)) raises(NotImplementedError, lambda: periodicity(sin(m), m[0, 0])) raises(NotImplementedError, lambda: periodicity(sin(m[0, 0]), m[0, 0])) def test_periodicity_check(): x = Symbol('x') y = Symbol('y') assert periodicity(tan(x), x, check=True) == pi assert periodicity(sin(x) + cos(x), x, check=True) == 2*pi assert periodicity(sec(x), x) == 2*pi assert periodicity(sin(x*y), x) == 2*pi/abs(y) assert periodicity(Abs(sec(sec(x))), x) == pi def test_lcim(): assert lcim([S.Half, S(2), S(3)]) == 6 assert lcim([pi/2, pi/4, pi]) == pi assert lcim([2*pi, pi/2]) == 2*pi assert lcim([S.One, 2*pi]) is None assert lcim([S(2) + 2*E, E/3 + Rational(1, 3), S.One + E]) == S(2) + 2*E def test_is_convex(): assert is_convex(1/x, x, domain=Interval.open(0, oo)) == True assert is_convex(1/x, x, domain=Interval(-oo, 0)) == False assert is_convex(x**2, x, domain=Interval(0, oo)) == True assert is_convex(1/x**3, x, domain=Interval.Lopen(0, oo)) == True assert is_convex(-1/x**3, x, domain=Interval.Ropen(-oo, 0)) == True assert is_convex(log(x), x) == False raises(NotImplementedError, lambda: is_convex(log(x), x, a)) def test_stationary_points(): x, y = symbols('x y') assert stationary_points(sin(x), x, Interval(-pi/2, pi/2) ) == {-pi/2, pi/2} assert stationary_points(sin(x), x, Interval.Ropen(0, pi/4) ) is S.EmptySet assert stationary_points(tan(x), x, ) is S.EmptySet assert stationary_points(sin(x)*cos(x), x, Interval(0, pi) ) == {pi/4, pi*Rational(3, 4)} assert stationary_points(sec(x), x, Interval(0, pi) ) == {0, pi} assert stationary_points((x+3)*(x-2), x ) == FiniteSet(Rational(-1, 2)) assert stationary_points((x + 3)/(x - 2), x, Interval(-5, 5) ) is S.EmptySet assert stationary_points((x**2+3)/(x-2), x ) == {2 - sqrt(7), 2 + sqrt(7)} assert stationary_points((x**2+3)/(x-2), x, Interval(0, 5) ) == {2 + sqrt(7)} assert stationary_points(x**4 + x**3 - 5*x**2, x, S.Reals ) == FiniteSet(-2, 0, Rational(5, 4)) assert stationary_points(exp(x), x ) is S.EmptySet assert stationary_points(log(x) - x, x, S.Reals ) == {1} assert stationary_points(cos(x), x, Union(Interval(0, 5), Interval(-6, -3)) ) == {0, -pi, pi} assert stationary_points(y, x, S.Reals ) == S.Reals assert stationary_points(y, x, S.EmptySet) == S.EmptySet def test_maximum(): x, y = symbols('x y') assert maximum(sin(x), x) is S.One assert maximum(sin(x), x, Interval(0, 1)) == sin(1) assert maximum(tan(x), x) is oo assert maximum(tan(x), x, Interval(-pi/4, pi/4)) is S.One assert maximum(sin(x)*cos(x), x, S.Reals) == S.Half assert simplify(maximum(sin(x)*cos(x), x, Interval(pi*Rational(3, 8), pi*Rational(5, 8))) ) == sqrt(2)/4 assert maximum((x+3)*(x-2), x) is oo assert maximum((x+3)*(x-2), x, Interval(-5, 0)) == S(14) assert maximum((x+3)/(x-2), x, Interval(-5, 0)) == Rational(2, 7) assert simplify(maximum(-x**4-x**3+x**2+10, x) ) == 41*sqrt(41)/512 + Rational(5419, 512) assert maximum(exp(x), x, Interval(-oo, 2)) == exp(2) assert maximum(log(x) - x, x, S.Reals) is S.NegativeOne assert maximum(cos(x), x, Union(Interval(0, 5), Interval(-6, -3)) ) is S.One assert maximum(cos(x)-sin(x), x, S.Reals) == sqrt(2) assert maximum(y, x, S.Reals) == y assert maximum(abs(a**3 + a), a, Interval(0, 2)) == 10 assert maximum(abs(60*a**3 + 24*a), a, Interval(0, 2)) == 528 assert maximum(abs(12*a*(5*a**2 + 2)), a, Interval(0, 2)) == 528 assert maximum(x/sqrt(x**2+1), x, S.Reals) == 1 raises(ValueError, lambda : maximum(sin(x), x, S.EmptySet)) raises(ValueError, lambda : maximum(log(cos(x)), x, S.EmptySet)) raises(ValueError, lambda : maximum(1/(x**2 + y**2 + 1), x, S.EmptySet)) raises(ValueError, lambda : maximum(sin(x), sin(x))) raises(ValueError, lambda : maximum(sin(x), x*y, S.EmptySet)) raises(ValueError, lambda : maximum(sin(x), S.One)) def test_minimum(): x, y = symbols('x y') assert minimum(sin(x), x) is S.NegativeOne assert minimum(sin(x), x, Interval(1, 4)) == sin(4) assert minimum(tan(x), x) is -oo assert minimum(tan(x), x, Interval(-pi/4, pi/4)) is S.NegativeOne assert minimum(sin(x)*cos(x), x, S.Reals) == Rational(-1, 2) assert simplify(minimum(sin(x)*cos(x), x, Interval(pi*Rational(3, 8), pi*Rational(5, 8))) ) == -sqrt(2)/4 assert minimum((x+3)*(x-2), x) == Rational(-25, 4) assert minimum((x+3)/(x-2), x, Interval(-5, 0)) == Rational(-3, 2) assert minimum(x**4-x**3+x**2+10, x) == S(10) assert minimum(exp(x), x, Interval(-2, oo)) == exp(-2) assert minimum(log(x) - x, x, S.Reals) is -oo assert minimum(cos(x), x, Union(Interval(0, 5), Interval(-6, -3)) ) is S.NegativeOne assert minimum(cos(x)-sin(x), x, S.Reals) == -sqrt(2) assert minimum(y, x, S.Reals) == y assert minimum(x/sqrt(x**2+1), x, S.Reals) == -1 raises(ValueError, lambda : minimum(sin(x), x, S.EmptySet)) raises(ValueError, lambda : minimum(log(cos(x)), x, S.EmptySet)) raises(ValueError, lambda : minimum(1/(x**2 + y**2 + 1), x, S.EmptySet)) raises(ValueError, lambda : minimum(sin(x), sin(x))) raises(ValueError, lambda : minimum(sin(x), x*y, S.EmptySet)) raises(ValueError, lambda : minimum(sin(x), S.One)) def test_issue_19869(): t = symbols('t') assert (maximum(sqrt(3)*(t - 1)/(3*sqrt(t**2 + 1)), t) ) == sqrt(3)/3 def test_issue_16469(): x = Symbol("x", real=True) f = abs(x) assert function_range(f, x, S.Reals) == Interval(0, oo, False, True) @_both_exp_pow def test_issue_18747(): assert periodicity(exp(pi*I*(x/4+S.Half/2)), x) == 8