add read me

venv/lib/python3.12/site-packages/sympy/assumptions/handlers/calculus.py

@@ -0,0 +1,273 @@
+"""
+This module contains query handlers responsible for calculus queries:
+infinitesimal, finite, etc.
+"""
+
+from sympy.assumptions import Q, ask
+from sympy.core import Expr, Add, Mul, Pow, Symbol
+from sympy.core.numbers import (NegativeInfinity, GoldenRatio,
+    Infinity, Exp1, ComplexInfinity, ImaginaryUnit, NaN, Number, Pi, E,
+    TribonacciConstant)
+from sympy.functions import cos, exp, log, sign, sin
+from sympy.logic.boolalg import conjuncts
+
+from ..predicates.calculus import (FinitePredicate, InfinitePredicate,
+    PositiveInfinitePredicate, NegativeInfinitePredicate)
+
+
+# FinitePredicate
+
+
+@FinitePredicate.register(Symbol)
+def _(expr, assumptions):
+    """
+    Handles Symbol.
+    """
+    if expr.is_finite is not None:
+        return expr.is_finite
+    if Q.finite(expr) in conjuncts(assumptions):
+        return True
+    return None
+
+@FinitePredicate.register(Add)
+def _(expr, assumptions):
+    """
+    Return True if expr is bounded, False if not and None if unknown.
+
+    Truth Table:
+
+    +-------+-----+-----------+-----------+
+    |       |     |           |           |
+    |       |  B  |     U     |     ?     |
+    |       |     |           |           |
+    +-------+-----+---+---+---+---+---+---+
+    |       |     |   |   |   |   |   |   |
+    |       |     |'+'|'-'|'x'|'+'|'-'|'x'|
+    |       |     |   |   |   |   |   |   |
+    +-------+-----+---+---+---+---+---+---+
+    |       |     |           |           |
+    |   B   |  B  |     U     |     ?     |
+    |       |     |           |           |
+    +---+---+-----+---+---+---+---+---+---+
+    |   |   |     |   |   |   |   |   |   |
+    |   |'+'|     | U | ? | ? | U | ? | ? |
+    |   |   |     |   |   |   |   |   |   |
+    |   +---+-----+---+---+---+---+---+---+
+    |   |   |     |   |   |   |   |   |   |
+    | U |'-'|     | ? | U | ? | ? | U | ? |
+    |   |   |     |   |   |   |   |   |   |
+    |   +---+-----+---+---+---+---+---+---+
+    |   |   |     |           |           |
+    |   |'x'|     |     ?     |     ?     |
+    |   |   |     |           |           |
+    +---+---+-----+---+---+---+---+---+---+
+    |       |     |           |           |
+    |   ?   |     |           |     ?     |
+    |       |     |           |           |
+    +-------+-----+-----------+---+---+---+
+
+        * 'B' = Bounded
+
+        * 'U' = Unbounded
+
+        * '?' = unknown boundedness
+
+        * '+' = positive sign
+
+        * '-' = negative sign
+
+        * 'x' = sign unknown
+
+        * All Bounded -> True
+
+        * 1 Unbounded and the rest Bounded -> False
+
+        * >1 Unbounded, all with same known sign -> False
+
+        * Any Unknown and unknown sign -> None
+
+        * Else -> None
+
+    When the signs are not the same you can have an undefined
+    result as in oo - oo, hence 'bounded' is also undefined.
+    """
+    sign = -1  # sign of unknown or infinite
+    result = True
+    for arg in expr.args:
+        _bounded = ask(Q.finite(arg), assumptions)
+        if _bounded:
+            continue
+        s = ask(Q.extended_positive(arg), assumptions)
+        # if there has been more than one sign or if the sign of this arg
+        # is None and Bounded is None or there was already
+        # an unknown sign, return None
+        if sign != -1 and s != sign or \
+                s is None and None in (_bounded, sign):
+            return None
+        else:
+            sign = s
+        # once False, do not change
+        if result is not False:
+            result = _bounded
+    return result
+
+@FinitePredicate.register(Mul)
+def _(expr, assumptions):
+    """
+    Return True if expr is bounded, False if not and None if unknown.
+
+    Truth Table:
+
+    +---+---+---+--------+
+    |   |   |   |        |
+    |   | B | U |   ?    |
+    |   |   |   |        |
+    +---+---+---+---+----+
+    |   |   |   |   |    |
+    |   |   |   | s | /s |
+    |   |   |   |   |    |
+    +---+---+---+---+----+
+    |   |   |   |        |
+    | B | B | U |   ?    |
+    |   |   |   |        |
+    +---+---+---+---+----+
+    |   |   |   |   |    |
+    | U |   | U | U | ?  |
+    |   |   |   |   |    |
+    +---+---+---+---+----+
+    |   |   |   |        |
+    | ? |   |   |   ?    |
+    |   |   |   |        |
+    +---+---+---+---+----+
+
+        * B = Bounded
+
+        * U = Unbounded
+
+        * ? = unknown boundedness
+
+        * s = signed (hence nonzero)
+
+        * /s = not signed
+    """
+    result = True
+    possible_zero = False
+    for arg in expr.args:
+        _bounded = ask(Q.finite(arg), assumptions)
+        if _bounded:
+            if ask(Q.zero(arg), assumptions) is not False:
+                if result is False:
+                    return None
+                possible_zero = True
+        elif _bounded is None:
+            if result is None:
+                return None
+            if ask(Q.extended_nonzero(arg), assumptions) is None:
+                return None
+            if result is not False:
+                result = None
+        else:
+            if possible_zero:
+                return None
+            result = False
+    return result
+
+@FinitePredicate.register(Pow)
+def _(expr, assumptions):
+    """
+    * Unbounded ** NonZero -> Unbounded
+
+    * Bounded ** Bounded -> Bounded
+
+    * Abs()<=1 ** Positive -> Bounded
+
+    * Abs()>=1 ** Negative -> Bounded
+
+    * Otherwise unknown
+    """
+    if expr.base == E:
+        return ask(Q.finite(expr.exp), assumptions)
+
+    base_bounded = ask(Q.finite(expr.base), assumptions)
+    exp_bounded = ask(Q.finite(expr.exp), assumptions)
+    if base_bounded is None and exp_bounded is None:  # Common Case
+        return None
+    if base_bounded is False and ask(Q.extended_nonzero(expr.exp), assumptions):
+        return False
+    if base_bounded and exp_bounded:
+        is_base_zero = ask(Q.zero(expr.base),assumptions)
+        is_exp_negative = ask(Q.negative(expr.exp),assumptions)
+        if is_base_zero is True and is_exp_negative is True:
+            return False
+        if is_base_zero is not False and is_exp_negative is not False:
+            return None
+        return True
+    if (abs(expr.base) <= 1) == True and ask(Q.extended_positive(expr.exp), assumptions):
+        return True
+    if (abs(expr.base) >= 1) == True and ask(Q.extended_negative(expr.exp), assumptions):
+        return True
+    if (abs(expr.base) >= 1) == True and exp_bounded is False:
+        return False
+    return None
+
+@FinitePredicate.register(exp)
+def _(expr, assumptions):
+    return ask(Q.finite(expr.exp), assumptions)
+
+@FinitePredicate.register(log)
+def _(expr, assumptions):
+    # After complex -> finite fact is registered to new assumption system,
+    # querying Q.infinite may be removed.
+    if ask(Q.infinite(expr.args[0]), assumptions):
+        return False
+    return ask(~Q.zero(expr.args[0]), assumptions)
+
+@FinitePredicate.register_many(cos, sin, Number, Pi, Exp1, GoldenRatio,
+    TribonacciConstant, ImaginaryUnit, sign)
+def _(expr, assumptions):
+    return True
+
+@FinitePredicate.register_many(ComplexInfinity, Infinity, NegativeInfinity)
+def _(expr, assumptions):
+    return False
+
+@FinitePredicate.register(NaN)
+def _(expr, assumptions):
+    return None
+
+
+# InfinitePredicate
+
+
+@InfinitePredicate.register(Expr)
+def _(expr, assumptions):
+    is_finite = Q.finite(expr)._eval_ask(assumptions)
+    if is_finite is None:
+        return None
+    return not is_finite
+
+
+# PositiveInfinitePredicate
+
+
+@PositiveInfinitePredicate.register(Infinity)
+def _(expr, assumptions):
+    return True
+
+
+@PositiveInfinitePredicate.register_many(NegativeInfinity, ComplexInfinity)
+def _(expr, assumptions):
+    return False
+
+
+# NegativeInfinitePredicate
+
+
+@NegativeInfinitePredicate.register(NegativeInfinity)
+def _(expr, assumptions):
+    return True
+
+
+@NegativeInfinitePredicate.register_many(Infinity, ComplexInfinity)
+def _(expr, assumptions):
+    return False