1"Implements Tight" 

2from .set import ConstraintSet 

3from ..nomials import PosynomialInequality, SignomialInequality 

4from ..small_scripts import mag 

5from ..small_scripts import appendsolwarning 

6from .. import SignomialsEnabled 

7 

8 

9class Tight(ConstraintSet): 

10 "ConstraintSet whose inequalities must result in an equality." 

11 reltol = 1e-3 

12 

13 def __init__(self, constraints, *, reltol=None, **kwargs): 

14 super().__init__(constraints) 

15 self.reltol = reltol or self.reltol 

16 self.__dict__.update(kwargs) # NOTE: for Berk's use in labelling 

17 

18 def process_result(self, result): 

19 "Checks that all constraints are satisfied with equality" 

20 super().process_result(result) 

21 variables = result["variables"] 

22 for constraint in self.flat(): 

23 rel_diff = 0 

24 if isinstance(constraint, PosynomialInequality): 

25 leftsubbed = constraint.left.sub(variables).value 

26 rightsubbed = constraint.right.sub(variables).value 

27 rel_diff = abs(1 - leftsubbed/rightsubbed) 

28 elif isinstance(constraint, SignomialInequality): 

29 siglt0, = constraint.unsubbed 

30 posy, negy = siglt0.posy_negy() 

31 posy = posy.sub(variables).value 

32 negy = negy.sub(variables).value 

33 rel_diff = abs(1 - posy/negy) 

34 if rel_diff >= self.reltol: 

35 # do another substitution for the sake of printing 

36 with SignomialsEnabled(): 

37 leftsubbed = constraint.left.sub(variables).value 

38 rightsubbed = constraint.right.sub(variables).value 

39 if rel_diff >= self.reltol: 

40 msg = ("Constraint [%.100s... %s %.100s...] is not tight:" 

41 " the left hand side evaluated to %s but" 

42 " the right hand side evaluated to %s" 

43 " (Allowable error: %s%%, Actual error: %.2g%%)" % 

44 (constraint.left, constraint.oper, constraint.right, 

45 leftsubbed, rightsubbed, 

46 self.reltol*100, mag(rel_diff)*100)) 

47 if hasattr(leftsubbed, "magnitude"): 

48 rightsubbed = rightsubbed.to(leftsubbed.units).magnitude 

49 leftsubbed = leftsubbed.magnitude 

50 constraint.tightvalues = (leftsubbed, constraint.oper, 

51 rightsubbed) 

52 constraint.rel_diff = rel_diff 

53 appendsolwarning(msg, constraint, result, 

54 "Unexpectedly Loose Constraints")