File size: 11,195 Bytes
6a86ad5
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
from sympy.core.numbers import (E, Rational, oo, pi, zoo)
from sympy.core.singleton import S
from sympy.core.symbol import Symbol
from sympy.functions.elementary.exponential import (exp, log)
from sympy.functions.elementary.miscellaneous import (Max, Min, sqrt)
from sympy.functions.elementary.trigonometric import (cos, sin, tan)
from sympy.calculus.accumulationbounds import AccumBounds
from sympy.core import Add, Mul, Pow
from sympy.core.expr import unchanged
from sympy.testing.pytest import raises, XFAIL
from sympy.abc import x

a = Symbol('a', real=True)
B = AccumBounds


def test_AccumBounds():
    assert B(1, 2).args == (1, 2)
    assert B(1, 2).delta is S.One
    assert B(1, 2).mid == Rational(3, 2)
    assert B(1, 3).is_real == True

    assert B(1, 1) is S.One

    assert B(1, 2) + 1 == B(2, 3)
    assert 1 + B(1, 2) == B(2, 3)
    assert B(1, 2) + B(2, 3) == B(3, 5)

    assert -B(1, 2) == B(-2, -1)

    assert B(1, 2) - 1 == B(0, 1)
    assert 1 - B(1, 2) == B(-1, 0)
    assert B(2, 3) - B(1, 2) == B(0, 2)

    assert x + B(1, 2) == Add(B(1, 2), x)
    assert a + B(1, 2) == B(1 + a, 2 + a)
    assert B(1, 2) - x == Add(B(1, 2), -x)

    assert B(-oo, 1) + oo == B(-oo, oo)
    assert B(1, oo) + oo is oo
    assert B(1, oo) - oo == B(-oo, oo)
    assert (-oo - B(-1, oo)) is -oo
    assert B(-oo, 1) - oo is -oo

    assert B(1, oo) - oo == B(-oo, oo)
    assert B(-oo, 1) - (-oo) == B(-oo, oo)
    assert (oo - B(1, oo)) == B(-oo, oo)
    assert (-oo - B(1, oo)) is -oo

    assert B(1, 2)/2 == B(S.Half, 1)
    assert 2/B(2, 3) == B(Rational(2, 3), 1)
    assert 1/B(-1, 1) == B(-oo, oo)

    assert abs(B(1, 2)) == B(1, 2)
    assert abs(B(-2, -1)) == B(1, 2)
    assert abs(B(-2, 1)) == B(0, 2)
    assert abs(B(-1, 2)) == B(0, 2)
    c = Symbol('c')
    raises(ValueError, lambda: B(0, c))
    raises(ValueError, lambda: B(1, -1))
    r = Symbol('r', real=True)
    raises(ValueError, lambda: B(r, r - 1))


def test_AccumBounds_mul():
    assert B(1, 2)*2 == B(2, 4)
    assert 2*B(1, 2) == B(2, 4)
    assert B(1, 2)*B(2, 3) == B(2, 6)
    assert B(0, 2)*B(2, oo) == B(0, oo)
    l, r = B(-oo, oo), B(-a, a)
    assert l*r == B(-oo, oo)
    assert r*l == B(-oo, oo)
    l, r = B(1, oo), B(-3, -2)
    assert l*r == B(-oo, -2)
    assert r*l == B(-oo, -2)
    assert B(1, 2)*0 == 0
    assert B(1, oo)*0 == B(0, oo)
    assert B(-oo, 1)*0 == B(-oo, 0)
    assert B(-oo, oo)*0 == B(-oo, oo)

    assert B(1, 2)*x == Mul(B(1, 2), x, evaluate=False)

    assert B(0, 2)*oo == B(0, oo)
    assert B(-2, 0)*oo == B(-oo, 0)
    assert B(0, 2)*(-oo) == B(-oo, 0)
    assert B(-2, 0)*(-oo) == B(0, oo)
    assert B(-1, 1)*oo == B(-oo, oo)
    assert B(-1, 1)*(-oo) == B(-oo, oo)
    assert B(-oo, oo)*oo == B(-oo, oo)


def test_AccumBounds_div():
    assert B(-1, 3)/B(3, 4) == B(Rational(-1, 3), 1)
    assert B(-2, 4)/B(-3, 4) == B(-oo, oo)
    assert B(-3, -2)/B(-4, 0) == B(S.Half, oo)

    # these two tests can have a better answer
    # after Union of B is improved
    assert B(-3, -2)/B(-2, 1) == B(-oo, oo)
    assert B(2, 3)/B(-2, 2) == B(-oo, oo)

    assert B(-3, -2)/B(0, 4) == B(-oo, Rational(-1, 2))
    assert B(2, 4)/B(-3, 0) == B(-oo, Rational(-2, 3))
    assert B(2, 4)/B(0, 3) == B(Rational(2, 3), oo)

    assert B(0, 1)/B(0, 1) == B(0, oo)
    assert B(-1, 0)/B(0, 1) == B(-oo, 0)
    assert B(-1, 2)/B(-2, 2) == B(-oo, oo)

    assert 1/B(-1, 2) == B(-oo, oo)
    assert 1/B(0, 2) == B(S.Half, oo)
    assert (-1)/B(0, 2) == B(-oo, Rational(-1, 2))
    assert 1/B(-oo, 0) == B(-oo, 0)
    assert 1/B(-1, 0) == B(-oo, -1)
    assert (-2)/B(-oo, 0) == B(0, oo)
    assert 1/B(-oo, -1) == B(-1, 0)

    assert B(1, 2)/a == Mul(B(1, 2), 1/a, evaluate=False)

    assert B(1, 2)/0 == B(1, 2)*zoo
    assert B(1, oo)/oo == B(0, oo)
    assert B(1, oo)/(-oo) == B(-oo, 0)
    assert B(-oo, -1)/oo == B(-oo, 0)
    assert B(-oo, -1)/(-oo) == B(0, oo)
    assert B(-oo, oo)/oo == B(-oo, oo)
    assert B(-oo, oo)/(-oo) == B(-oo, oo)
    assert B(-1, oo)/oo == B(0, oo)
    assert B(-1, oo)/(-oo) == B(-oo, 0)
    assert B(-oo, 1)/oo == B(-oo, 0)
    assert B(-oo, 1)/(-oo) == B(0, oo)


def test_issue_18795():
    r = Symbol('r', real=True)
    a = B(-1,1)
    c = B(7, oo)
    b = B(-oo, oo)
    assert c - tan(r) == B(7-tan(r), oo)
    assert b + tan(r) == B(-oo, oo)
    assert (a + r)/a == B(-oo, oo)*B(r - 1, r + 1)
    assert (b + a)/a == B(-oo, oo)


def test_AccumBounds_func():
    assert (x**2 + 2*x + 1).subs(x, B(-1, 1)) == B(-1, 4)
    assert exp(B(0, 1)) == B(1, E)
    assert exp(B(-oo, oo)) == B(0, oo)
    assert log(B(3, 6)) == B(log(3), log(6))


@XFAIL
def test_AccumBounds_powf():
    nn = Symbol('nn', nonnegative=True)
    assert B(1 + nn, 2 + nn)**B(1, 2) == B(1 + nn, (2 + nn)**2)
    i = Symbol('i', integer=True, negative=True)
    assert B(1, 2)**i == B(2**i, 1)


def test_AccumBounds_pow():
    assert B(0, 2)**2 == B(0, 4)
    assert B(-1, 1)**2 == B(0, 1)
    assert B(1, 2)**2 == B(1, 4)
    assert B(-1, 2)**3 == B(-1, 8)
    assert B(-1, 1)**0 == 1

    assert B(1, 2)**Rational(5, 2) == B(1, 4*sqrt(2))
    assert B(0, 2)**S.Half == B(0, sqrt(2))

    neg = Symbol('neg', negative=True)
    assert unchanged(Pow, B(neg, 1), S.Half)
    nn = Symbol('nn', nonnegative=True)
    assert B(nn, nn + 1)**S.Half == B(sqrt(nn), sqrt(nn + 1))
    assert B(nn, nn + 1)**nn == B(nn**nn, (nn + 1)**nn)
    assert unchanged(Pow, B(nn, nn + 1), x)
    i = Symbol('i', integer=True)
    assert B(1, 2)**i == B(Min(1, 2**i), Max(1, 2**i))
    i = Symbol('i', integer=True, nonnegative=True)
    assert B(1, 2)**i == B(1, 2**i)
    assert B(0, 1)**i == B(0**i, 1)

    assert B(1, 5)**(-2) == B(Rational(1, 25), 1)
    assert B(-1, 3)**(-2) == B(0, oo)
    assert B(0, 2)**(-3) == B(Rational(1, 8), oo)
    assert B(-2, 0)**(-3) == B(-oo, -Rational(1, 8))
    assert B(0, 2)**(-2) == B(Rational(1, 4), oo)
    assert B(-1, 2)**(-3) == B(-oo, oo)
    assert B(-3, -2)**(-3) == B(Rational(-1, 8), Rational(-1, 27))
    assert B(-3, -2)**(-2) == B(Rational(1, 9), Rational(1, 4))
    assert B(0, oo)**S.Half == B(0, oo)
    assert B(-oo, 0)**(-2) == B(0, oo)
    assert B(-2, 0)**(-2) == B(Rational(1, 4), oo)

    assert B(Rational(1, 3), S.Half)**oo is S.Zero
    assert B(0, S.Half)**oo is S.Zero
    assert B(S.Half, 1)**oo == B(0, oo)
    assert B(0, 1)**oo == B(0, oo)
    assert B(2, 3)**oo is oo
    assert B(1, 2)**oo == B(0, oo)
    assert B(S.Half, 3)**oo == B(0, oo)
    assert B(Rational(-1, 3), Rational(-1, 4))**oo is S.Zero
    assert B(-1, Rational(-1, 2))**oo is S.NaN
    assert B(-3, -2)**oo is zoo
    assert B(-2, -1)**oo is S.NaN
    assert B(-2, Rational(-1, 2))**oo is S.NaN
    assert B(Rational(-1, 2), S.Half)**oo is S.Zero
    assert B(Rational(-1, 2), 1)**oo == B(0, oo)
    assert B(Rational(-2, 3), 2)**oo == B(0, oo)
    assert B(-1, 1)**oo == B(-oo, oo)
    assert B(-1, S.Half)**oo == B(-oo, oo)
    assert B(-1, 2)**oo == B(-oo, oo)
    assert B(-2, S.Half)**oo == B(-oo, oo)

    assert B(1, 2)**x == Pow(B(1, 2), x, evaluate=False)

    assert B(2, 3)**(-oo) is S.Zero
    assert B(0, 2)**(-oo) == B(0, oo)
    assert B(-1, 2)**(-oo) == B(-oo, oo)

    assert (tan(x)**sin(2*x)).subs(x, B(0, pi/2)) == \
        Pow(B(-oo, oo), B(0, 1))


def test_AccumBounds_exponent():
    # base is 0
    z = 0**B(a, a + S.Half)
    assert z.subs(a, 0) == B(0, 1)
    assert z.subs(a, 1) == 0
    p = z.subs(a, -1)
    assert p.is_Pow and p.args == (0, B(-1, -S.Half))
    # base > 0
    #   when base is 1 the type of bounds does not matter
    assert 1**B(a, a + 1) == 1
    #  otherwise we need to know if 0 is in the bounds
    assert S.Half**B(-2, 2) == B(S(1)/4, 4)
    assert 2**B(-2, 2) == B(S(1)/4, 4)

    # +eps may introduce +oo
    # if there is a negative integer exponent
    assert B(0, 1)**B(S(1)/2, 1) == B(0, 1)
    assert B(0, 1)**B(0, 1) == B(0, 1)

    # positive bases have positive bounds
    assert B(2, 3)**B(-3, -2) == B(S(1)/27, S(1)/4)
    assert B(2, 3)**B(-3, 2) == B(S(1)/27, 9)

    # bounds generating imaginary parts unevaluated
    assert unchanged(Pow, B(-1, 1), B(1, 2))
    assert B(0, S(1)/2)**B(1, oo) == B(0, S(1)/2)
    assert B(0, 1)**B(1, oo) == B(0, oo)
    assert B(0, 2)**B(1, oo) == B(0, oo)
    assert B(0, oo)**B(1, oo) == B(0, oo)
    assert B(S(1)/2, 1)**B(1, oo) == B(0, oo)
    assert B(S(1)/2, 1)**B(-oo, -1) == B(0, oo)
    assert B(S(1)/2, 1)**B(-oo, oo) == B(0, oo)
    assert B(S(1)/2, 2)**B(1, oo) == B(0, oo)
    assert B(S(1)/2, 2)**B(-oo, -1) == B(0, oo)
    assert B(S(1)/2, 2)**B(-oo, oo) == B(0, oo)
    assert B(S(1)/2, oo)**B(1, oo) == B(0, oo)
    assert B(S(1)/2, oo)**B(-oo, -1) == B(0, oo)
    assert B(S(1)/2, oo)**B(-oo, oo) == B(0, oo)
    assert B(1, 2)**B(1, oo) == B(0, oo)
    assert B(1, 2)**B(-oo, -1) == B(0, oo)
    assert B(1, 2)**B(-oo, oo) == B(0, oo)
    assert B(1, oo)**B(1, oo) == B(0, oo)
    assert B(1, oo)**B(-oo, -1) == B(0, oo)
    assert B(1, oo)**B(-oo, oo) == B(0, oo)
    assert B(2, oo)**B(1, oo) == B(2, oo)
    assert B(2, oo)**B(-oo, -1) == B(0, S(1)/2)
    assert B(2, oo)**B(-oo, oo) == B(0, oo)


def test_comparison_AccumBounds():
    assert (B(1, 3) < 4) == S.true
    assert (B(1, 3) < -1) == S.false
    assert (B(1, 3) < 2).rel_op == '<'
    assert (B(1, 3) <= 2).rel_op == '<='

    assert (B(1, 3) > 4) == S.false
    assert (B(1, 3) > -1) == S.true
    assert (B(1, 3) > 2).rel_op == '>'
    assert (B(1, 3) >= 2).rel_op == '>='

    assert (B(1, 3) < B(4, 6)) == S.true
    assert (B(1, 3) < B(2, 4)).rel_op == '<'
    assert (B(1, 3) < B(-2, 0)) == S.false

    assert (B(1, 3) <= B(4, 6)) == S.true
    assert (B(1, 3) <= B(-2, 0)) == S.false

    assert (B(1, 3) > B(4, 6)) == S.false
    assert (B(1, 3) > B(-2, 0)) == S.true

    assert (B(1, 3) >= B(4, 6)) == S.false
    assert (B(1, 3) >= B(-2, 0)) == S.true

    # issue 13499
    assert (cos(x) > 0).subs(x, oo) == (B(-1, 1) > 0)

    c = Symbol('c')
    raises(TypeError, lambda: (B(0, 1) < c))
    raises(TypeError, lambda: (B(0, 1) <= c))
    raises(TypeError, lambda: (B(0, 1) > c))
    raises(TypeError, lambda: (B(0, 1) >= c))


def test_contains_AccumBounds():
    assert (1 in B(1, 2)) == S.true
    raises(TypeError, lambda: a in B(1, 2))
    assert 0 in B(-1, 0)
    raises(TypeError, lambda:
        (cos(1)**2 + sin(1)**2 - 1) in B(-1, 0))
    assert (-oo in B(1, oo)) == S.true
    assert (oo in B(-oo, 0)) == S.true

    # issue 13159
    assert Mul(0, B(-1, 1)) == Mul(B(-1, 1), 0) == 0
    import itertools
    for perm in itertools.permutations([0, B(-1, 1), x]):
        assert Mul(*perm) == 0


def test_intersection_AccumBounds():
    assert B(0, 3).intersection(B(1, 2)) == B(1, 2)
    assert B(0, 3).intersection(B(1, 4)) == B(1, 3)
    assert B(0, 3).intersection(B(-1, 2)) == B(0, 2)
    assert B(0, 3).intersection(B(-1, 4)) == B(0, 3)
    assert B(0, 1).intersection(B(2, 3)) == S.EmptySet
    raises(TypeError, lambda: B(0, 3).intersection(1))


def test_union_AccumBounds():
    assert B(0, 3).union(B(1, 2)) == B(0, 3)
    assert B(0, 3).union(B(1, 4)) == B(0, 4)
    assert B(0, 3).union(B(-1, 2)) == B(-1, 3)
    assert B(0, 3).union(B(-1, 4)) == B(-1, 4)
    raises(TypeError, lambda: B(0, 3).union(1))