X-Git-Url: https://svn.cri.ensmp.fr/git/linpy.git/blobdiff_plain/4540f520e6ae625c360c50ea2f4abf07d6811780..6d08d8c0a84c1ffa31f5eb16e33b340727f46175:/linpy/domains.py

diff --git a/linpy/domains.py b/linpy/domains.py
index 799b99d..1f7a190 100644
--- a/linpy/domains.py
+++ b/linpy/domains.py
@@ -24,7 +24,7 @@ from fractions import Fraction
 
 from . import islhelper
 from .islhelper import mainctx, libisl
-from .linexprs import LinExpr, Symbol, Rational
+from .linexprs import LinExpr, Symbol
 from .geometry import GeometricObject, Point, Vector
 
 
@@ -38,7 +38,7 @@ __all__ = [
 class Domain(GeometricObject):
     """
     A domain is a union of polyhedra. Unlike polyhedra, domains allow exact
-    computation of union and complementary operations.
+    computation of union, subtraction and complementary operations.
 
     A domain with a unique polyhedron is automatically subclassed as a
     Polyhedron instance.
@@ -54,22 +54,23 @@ class Domain(GeometricObject):
         """
         Return a domain from a sequence of polyhedra.
 
-        >>> square = Polyhedron('0 <= x <= 2, 0 <= y <= 2')
-        >>> square2 = Polyhedron('2 <= x <= 4, 2 <= y <= 4')
-        >>> dom = Domain([square, square2])
+        >>> square1 = Polyhedron('0 <= x <= 2, 0 <= y <= 2')
+        >>> square2 = Polyhedron('1 <= x <= 3, 1 <= y <= 3')
+        >>> dom = Domain(square1, square2)
+        >>> dom
+        Or(And(x <= 2, 0 <= x, y <= 2, 0 <= y),
+           And(x <= 3, 1 <= x, y <= 3, 1 <= y))
 
         It is also possible to build domains from polyhedra using arithmetic
-        operators Domain.__and__(), Domain.__or__() or functions And() and Or(),
-        using one of the following instructions:
+        operators Domain.__or__(), Domain.__invert__() or functions Or() and
+        Not(), using one of the following instructions:
 
-        >>> square = Polyhedron('0 <= x <= 2, 0 <= y <= 2')
-        >>> square2 = Polyhedron('2 <= x <= 4, 2 <= y <= 4')
-        >>> dom = square | square2
-        >>> dom = Or(square, square2)
+        >>> dom = square1 | square2
+        >>> dom = Or(square1, square2)
 
         Alternatively, a domain can be built from a string:
 
-        >>> dom = Domain('0 <= x <= 2, 0 <= y <= 2; 2 <= x <= 4, 2 <= y <= 4')
+        >>> dom = Domain('0 <= x <= 2, 0 <= y <= 2; 1 <= x <= 3, 1 <= y <= 3')
 
         Finally, a domain can be built from a GeometricObject instance, calling
         the GeometricObject.asdomain() method.
@@ -703,17 +704,17 @@ class Domain(GeometricObject):
         Create a domain from a string. Raise SyntaxError if the string is not
         properly formatted.
         """
-        # remove curly brackets
+        # Remove curly brackets.
         string = cls._RE_BRACES.sub(r'', string)
-        # replace '=' by '=='
+        # Replace '=' by '=='.
         string = cls._RE_EQ.sub(r'\1==\2', string)
-        # replace 'and', 'or', 'not'
+        # Replace 'and', 'or', 'not'.
         string = cls._RE_AND.sub(r' & ', string)
         string = cls._RE_OR.sub(r' | ', string)
         string = cls._RE_NOT.sub(r' ~', string)
-        # add implicit multiplication operators, e.g. '5x' -> '5*x'
+        # Add implicit multiplication operators, e.g. '5x' -> '5*x'.
         string = cls._RE_NUM_VAR.sub(r'\1*\2', string)
-        # add parentheses to force precedence
+        # Add parentheses to force precedence.
         tokens = cls._RE_OPERATORS.split(string)
         for i, token in enumerate(tokens):
             if i % 2 == 0: