-
Notifications
You must be signed in to change notification settings - Fork 40
/
relaxation.py
52 lines (41 loc) · 1.48 KB
/
relaxation.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
"Relaxation examples"
from gpkit import Variable, Model
x = Variable("x")
x_min = Variable("x_min", 2)
x_max = Variable("x_max", 1)
m = Model(x, [x <= x_max, x >= x_min])
print("Original model")
print("==============")
print(m)
print("")
# m.solve() # raises a RuntimeWarning!
print("With constraints relaxed equally")
print("================================")
from gpkit.constraints.relax import ConstraintsRelaxedEqually
allrelaxed = ConstraintsRelaxedEqually(m)
mr1 = Model(allrelaxed.relaxvar, allrelaxed)
print(mr1)
print(mr1.solve(verbosity=0).table()) # solves with an x of 1.414
from gpkit.breakdowns import Breakdowns
Breakdowns(mr1.solution).trace("cost")
print("")
print("With constraints relaxed individually")
print("=====================================")
from gpkit.constraints.relax import ConstraintsRelaxed
constraintsrelaxed = ConstraintsRelaxed(m)
mr2 = Model(constraintsrelaxed.relaxvars.prod() * m.cost**0.01,
# add a bit of the original cost in
constraintsrelaxed)
print(mr2)
print(mr2.solve(verbosity=0).table()) # solves with an x of 1.0
print("")
print("With constants relaxed individually")
print("===================================")
from gpkit.constraints.relax import ConstantsRelaxed
constantsrelaxed = ConstantsRelaxed(m)
mr3 = Model(constantsrelaxed.relaxvars.prod() * m.cost**0.01,
# add a bit of the original cost in
constantsrelaxed)
print(mr3)
print(mr3.solve(verbosity=0).table()) # brings x_min down to 1.0
print("")