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Add BoneMarketModel.AddDivisionApproximateExponentiationEquality 

This method combines two common operations, avoiding the need for
intermediate variables at the call site.
This commit is contained in:
Jeremy Saklad 2021-10-16 10:22:31 -05:00
parent b5a047889d
commit 9671190059
Signed by: Jeremy Saklad
GPG Key ID: 9CA2149583EDBF84
1 changed files with 16 additions and 0 deletions
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bonemarketsolver/objects/bone_market_model.py
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@ -22,6 +22,22 @@ Set `upto` to a value that is unlikely to come into play.
Each parameter is interpreted as a BoundedLinearExpression, and a layer of indirection is applied such that each Constraint in the returned tuple can accept an enforcement literal."""
return self.AddAllowedAssignments((target, var), ((int(base**exp), base) for base in range(upto + 1)))
def AddDivisionApproximateExponentiationEquality(self, target, num, denom, exp, upto):
"""Adds `target == (num // denom)**exp` using a lookup table.
Set `upto` to a value that is unlikely to come into play.
`target`, `num`, and `denom` are interpreted as a BoundedLinearExpression, and a layer of indirection is applied such that each Constraint in the returned tuple can accept an enforcement literal."""
quotient = self.NewIntVar(f'{repr(target)} == ({repr(num)} // {repr(denom)})**{repr(exp)}: quotient')
intermediate_num, num_constraint = self.NewIntermediateIntVar(num, f'{repr(target)} == ({repr(num)} // {repr(denom)})**{repr(exp)}: num', lb = 0)
intermediate_denom, denom_constraint = self.NewIntermediateIntVar(denom, f'{repr(target)} == ({repr(num)} // {repr(denom)})**{repr(exp)}: denom', lb = 1)
intermediate_target, target_constraint = self.NewIntermediateIntVar(target, f'{repr(target)} == ({repr(num)} // {repr(denom)})**{repr(exp)}: target')
super().AddDivisionEquality(quotient, intermediate_num, intermediate_denom)
super().AddAllowedAssignments((intermediate_target, quotient), ((int(base**exp), base) for base in range(upto + 1)))
return (num_constraint, denom_constraint, target_constraint)
def AddDivisionEquality(self, target, num, denom):
"""Adds `target == num // denom` (integer division rounded towards 0).