def calculate_absolute_uncertainty(
self,
*assumptions: List[AppliedPredicate],
refine: bool = False,
delta_char: str = '\\Delta ') -> 'Expression':
"""Calculate the absolute uncertainty in the expression (IB way), assuming all args given are independent.
:return: the absolute uncertainty of this expression
:rtype: Expression
>>> Expression([a], c * a).calculate_absolute_uncertainty(sympy.Q.positive(c), refine=True, delta_char='Δ')
f(Δa) = c*Δa
>>> Expression([a, b, c], a + b - c).calculate_absolute_uncertainty(refine=True, delta_char='Δ')
f(Δa, Δb, Δc) = Δa + Δb + Δc
"""
uncertainty_expr = sympy.Integer(0) # just in case
uncertainty_args = []
global_assumptions.add(*assumptions)
for var in self.args:
d_var = sympy.Symbol(delta_char + sympy.latex(var))
uncertainty_args.append(d_var)
uncertainty_expr += sympy.Abs(self.expr.diff(var)) * d_var
global_assumptions.add(sympy.Q.positive(var))
if refine:
uncertainty_expr = sympy.refine(uncertainty_expr)
global_assumptions.clear()
return Expression(uncertainty_args, uncertainty_expr)
def switch_context(self, context):
self.previous_context.append(self.context)
self.context = context
global_assumptions.clear()
global_assumptions.update(self.context.assumptions)
def restore(self):
if self.previous is None:
return
self.assumptions.update(global_assumptions)
global_assumptions.clear()
global_assumptions.update(self.previous.assumptions)
def switch(self):
global context
self.previous = context
context = self
global_assumptions.clear()
global_assumptions.update(self.assumptions)
def test_remove_safe():
global_assumptions.add(Q.integer(x))
with assuming():
assert ask(Q.integer(x))
global_assumptions.remove(Q.integer(x))
assert not ask(Q.integer(x))
assert ask(Q.integer(x))
global_assumptions.clear() # for the benefit of other tests
def test_remove_safe():
global_assumptions.add(Q.integer(x))
with assuming():
assert ask(Q.integer(x))
global_assumptions.remove(Q.integer(x))
assert not ask(Q.integer(x))
assert ask(Q.integer(x))
global_assumptions.clear() # for the benefit of other tests
def restore_context(self):
self.context.assumptions.update(global_assumptions)
self.context = self.previous_context.pop()
global_assumptions.clear()
global_assumptions.update(self.context.assumptions)
def restore(self):
if self.previous is None:
return
self.assumptions.update(global_assumptions)
global_assumptions.clear()
global_assumptions.update(self.previous.assumptions)
def switch(self):
global context
self.previous = context
context = self
global_assumptions.clear()
global_assumptions.update(self.assumptions)
def test_global():
"""Test for global assumptions"""
global_assumptions.add(Q.is_true(x > 0))
assert Q.is_true(x > 0) in global_assumptions
global_assumptions.remove(Q.is_true(x > 0))
assert not Q.is_true(x > 0) in global_assumptions
# same with multiple of assumptions
global_assumptions.add(Q.is_true(x > 0), Q.is_true(y > 0))
assert Q.is_true(x > 0) in global_assumptions
assert Q.is_true(y > 0) in global_assumptions
global_assumptions.clear()
assert not Q.is_true(x > 0) in global_assumptions
assert not Q.is_true(y > 0) in global_assumptions
def test_global():
"""Test for global assumptions"""
global_assumptions.add(Q.is_true(x > 0))
assert Q.is_true(x > 0) in global_assumptions
global_assumptions.remove(Q.is_true(x > 0))
assert not Q.is_true(x > 0) in global_assumptions
# same with multiple of assumptions
global_assumptions.add(Q.is_true(x > 0), Q.is_true(y > 0))
assert Q.is_true(x > 0) in global_assumptions
assert Q.is_true(y > 0) in global_assumptions
global_assumptions.clear()
assert not Q.is_true(x > 0) in global_assumptions
assert not Q.is_true(y > 0) in global_assumptions
def test_global():
"""Test for global assumptions"""
global_assumptions.add(x > 0)
assert (x > 0) in global_assumptions
global_assumptions.remove(x > 0)
assert not (x > 0) in global_assumptions
# same with multiple of assumptions
global_assumptions.add(x > 0, y > 0)
assert (x > 0) in global_assumptions
assert (y > 0) in global_assumptions
global_assumptions.clear()
assert not (x > 0) in global_assumptions
assert not (y > 0) in global_assumptions
