examples/nsad2010.py

   1 #!/usr/bin/env python3
   2
   3 from linpy import *
   4
   5
   6 class Transformer:
   7
   8     def __new__(cls, polyhedron, range_symbols, domain_symbols):
   9         self = object().__new__(cls)
  10         self.polyhedron = polyhedron
  11         self.range_symbols = range_symbols
  12         self.domain_symbols = domain_symbols
  13         return self
  14
  15     @property
  16     def symbols(self):
  17         return self.range_symbols + self.domain_symbols
  18
  19     def star(self):
  20         delta_symbols = [symbol.asdummy() for symbol in self.range_symbols]
  21         k = Dummy('k')
  22         polyhedron = self.polyhedron
  23         for x, xprime, dx in zip(self.range_symbols, self.domain_symbols, delta_symbols):
  24             polyhedron &= Eq(dx, xprime - x)
  25         polyhedron = polyhedron.project(self.symbols)
  26         equalities, inequalities = [], []
  27         for equality in polyhedron.equalities:
  28             equality += (k-1) * equality.constant
  29             equalities.append(equality)
  30         for inequality in polyhedron.inequalities:
  31             inequality += (k-1) * inequality.constant
  32             inequalities.append(inequality)
  33         polyhedron = Polyhedron(equalities, inequalities) & Ge(k, 0)
  34         polyhedron = polyhedron.project([k])
  35         for x, xprime, dx in zip(self.range_symbols, self.domain_symbols, delta_symbols):
  36             polyhedron &= Eq(dx, xprime - x)
  37         polyhedron = polyhedron.project(delta_symbols)
  38         return Transformer(polyhedron, self.range_symbols, self.domain_symbols)
  39
  40
  41 if __name__ == '__main__':
  42     i, iprime, j, jprime = symbols("i i' j j'")
  43     transformer = Transformer(Eq(iprime, i + 2) & Eq(jprime, j + 1),
  44         [i, j], [iprime, jprime])
  45     print('T  =', transformer.polyhedron)
  46     print('T* =', transformer.star().polyhedron)