def truthtable(self, start=0, end=-1):
r"""
This function returns a truthtable object corresponding to the given
statement. Each row of the table corresponds to a binary number, with
each variable associated to a column of the number, and taking on
a true value if that column has a value of 1. Please see the
logictable module for details. The function returns a table that
start inclusive and end exclusive so truthtable(0, 2) will include
row 0, but not row 2.
INPUT:
self -- the calling object.
start -- an integer representing the row of the truth
table from which to start initialized to 0, which
is the first row when all the variables are
false.
end -- an integer representing the last row of the truthtable
to be created. It is initialized to the last row of the
full table.
OUTPUT:
Returns the truthtable (a 2-D array with the creating statement
tacked on the front) corresponding to the statement.
EXAMPLES:
This example illustrates the creation of a statement.
sage: import sage.logic.propcalc as propcalc
sage: s = propcalc.formula("a&b|~(c|a)")
sage: s.truthtable()
a b c value
False False False True
False False True False
False True False True
False True True False
True False False False
True False True False
True True False True
True True True True
We can now create truthtable of rows 1 to 4, inclusive
sage: s.truthtable(1, 5)
a b c value
False False True False
False True False True
False True True False
True False False False
There should be no errors.
NOTES:
When sent with no start or end parameters, this is an
exponential time function requiring O(2**n) time, where
n is the number of variables in the expression.
"""
max = 2**len(self.__vars_order)
if (end < 0):
end = max
if (end > max):
end = max
if (start < 0):
start = 0
if (start > max):
start = max
keys, table = [], []
vars = {}
for var in self.__vars_order:
vars[var] = False
keys.insert(0, var)
keys = list(keys)
for i in range(start, end):
j = 0
row = []
for key in keys:
bit = self.get_bit(i, j)
vars[key] = bit
j += 1
row.insert(0, bit)
row.append(booleval.eval_formula(self.__tree, vars))
table.append(row)
keys.reverse()
table = logictable.Truthtable(table, keys)
return table
def truthtable(self, start=0, end=-1):
r"""
Return a truth table for the calling formula.
INPUT:
- ``self`` -- calling object
- ``start`` -- (default: 0) an integer. This is the first
row of the truth table to be created.
- ``end`` -- (default: -1) an integer. This is the laste
row of the truth table to be created.
OUTPUT:
The truth table as a 2-D array
EXAMPLES:
This example illustrates the creation of a truth table.
::
sage: import sage.logic.propcalc as propcalc
sage: s = propcalc.formula("a&b|~(c|a)")
sage: s.truthtable()
a b c value
False False False True
False False True False
False True False True
False True True False
True False False False
True False True False
True True False True
True True True True
We can now create a truthtable of rows 1 to 4, inclusive.
::
sage: s.truthtable(1, 5)
a b c value
False False True False
False True False True
False True True False
True False False False
.. NOTE::
Each row of the table corresponds to a binary number, with
each variable associated to a column of the number, and taking on
a true value if that column has a value of 1. Please see the
logictable module for details. The function returns a table that
start inclusive and end exclusive so truthtable(0, 2) will include
row 0, but not row 2.
When sent with no start or end parameters, this is an
exponential time function requiring O(2**n) time, where
n is the number of variables in the expression.
"""
max = 2**len(self.__vars_order)
if end < 0:
end = max
if end > max:
end = max
if start < 0:
start = 0
if start > max:
start = max
keys, table = [], []
vars = {}
for var in self.__vars_order:
vars[var] = False
keys.insert(0, var)
keys = list(keys)
for i in range(start, end):
j = 0
row = []
for key in keys:
bit = self.get_bit(i, j)
vars[key] = bit
j += 1
row.insert(0, bit)
row.append(booleval.eval_formula(self.__tree, vars))
table.append(row)
keys.reverse()
table = logictable.Truthtable(table, keys)
return table