A linear expression with no symbol, only a constant term, is automatically subclassed as a :class:`Rational` instance.
.. method:: coefficient(symbol)
- __getitem__(symbol)
+ __getitem__(symbol)
Return the coefficient value of the given symbol, or ``0`` if the symbol does not appear in the expression.
.. method:: __mul__(value)
- Return the product of the linear expression as a rational.
+ Return the product of the linear expression by a rational.
.. method:: __truediv__(value)
- Return the quotient of the linear expression as a rational.
+ Return the quotient of the linear expression by a rational.
.. method:: __eq__(expr)
As explained below, it is possible to create polyhedra from linear expressions using comparison methods.
.. method:: __lt__(expr)
- __le__(expr)
- __ge__(expr)
- __gt__(expr)
+ __le__(expr)
+ __ge__(expr)
+ __gt__(expr)
Create a new :class:`Polyhedron` instance whose unique constraint is the comparison between two linear expressions.
As an alternative, functions :func:`Lt`, :func:`Le`, :func:`Ge` and :func:`Gt` can be used.
Return the expression multiplied by its lowest common denominator to make all values integer.
.. method:: subs(symbol, expression)
- subs(pairs)
+ subs(pairs)
Substitute the given symbol by an expression and return the resulting expression.
Raise :exc:`TypeError` if the resulting expression is not linear.
.. classmethod:: fromsympy(expr)
Create a linear expression from a :mod:`sympy` expression.
- Raise :exc:`ValueError` is the :mod:`sympy` expression is not linear.
+ Raise :exc:`TypeError` is the :mod:`sympy` expression is not linear.
.. method:: tosympy()
Polyhedra
---------
-A *convex polyhedron* (or simply polyhedron) is the space defined by a system of linear equalities and inequalities.
+A *convex polyhedron* (or simply "polyhedron") is the space defined by a system of linear equalities and inequalities.
This space can be unbounded.
.. class:: Polyhedron(equalities, inequalities)
.. method:: widen(polyhedron)
- Compute the standard widening of two polyhedra, à la Halbwachs.
+ Compute the *standard widening* of two polyhedra, à la Halbwachs.
+
+ In its current implementation, this method is slow and should not be used on large polyhedra.
.. data:: Empty
.. attribute:: symbols
- The tuple of symbols present in the domain expression, sorted according to :meth:`Symbol.sortkey`.
+ The tuple of symbols present in the domain equations, sorted according to :meth:`Symbol.sortkey`.
.. attribute:: dimension
.. method:: __contains__(point)
- Return ``True`` if the :class:`Point` is contained within the domain.
+ Return ``True`` if the point is contained within the domain.
.. method:: faces()
Comparison and Logic Operators
------------------------------
-The following functions create :class:`Polyhedron` or :class:`Domain` instances by comparison of :class:`LinExpr` instances:
+The following functions create :class:`Polyhedron` or :class:`Domain` instances using the comparisons of two or more :class:`LinExpr` instances:
.. function:: Lt(expr1, expr2[, expr3, ...])
The dimension of the point, i.e. the number of symbols present in it.
.. method:: coordinate(symbol)
- __getitem__(symbol)
+ __getitem__(symbol)
Return the coordinate value of the given symbol.
Raise :exc:`KeyError` if the symbol is not involved in the point.
.. method:: __add__(vector)
- Translate the point by a :class:`Vector` instance and return the resulting point.
+ Translate the point by a :class:`Vector` object and return the resulting point.
.. method:: __sub__(point)
- __sub__(vector)
+ __sub__(vector)
The first version substracts a point from another and returns the resulting vector.
The second version translates the point by the opposite vector of *vector* and returns the resulting point.
.. class:: Vector(coordinates)
+ Vector(point1, point2)
- Create a point from a dictionary or a sequence that maps the symbols to their coordinates, similar to :meth:`Point`.
- Coordinates must be rational numbers.
+ The first version creates a vector from a dictionary or a sequence that maps the symbols to their coordinates, similarly to :meth:`Point`.
+ The second version creates a vector between two points.
:class:`Vector` instances are hashable and should be treated as immutable.
The dimension of the point, i.e. the number of symbols present in it.
.. method:: coordinate(symbol)
- __getitem__(symbol)
+ __getitem__(symbol)
Return the coordinate value of the given symbol.
Raise :exc:`KeyError` if the symbol is not involved in the point.
Return ``True`` if not all coordinates are ``0``.
.. method:: __add__(point)
- __add__(vector)
+ __add__(vector)
The first version translates the point *point* to the vector and returns the resulting point.
The second version adds vector *vector* to the vector and returns the resulting vector.
.. method:: __sub__(point)
- __sub__(vector)
+ __sub__(vector)
The first version substracts a point from a vector and returns the resulting point.
The second version returns the difference vector between two vectors.
Return the opposite vector.
+ .. method:: __mul__(value)
+
+ Multiply the vector by a scalar value and return the resulting vector.
+
+ .. method:: __truediv__(value)
+
+ Divide the vector by a scalar value and return the resulting vector.
+
+ .. method:: __eq__(vector)
+
+ Test whether two vectors are equal.
+
.. method:: angle(vector)
Retrieve the angle required to rotate the vector into the vector passed in argument.
.. method:: cross(vector)
Compute the cross product of two 3D vectors.
- If either one of the vectors is not tridimensional, a :exc:`ValueError` exception is raised.
+ If either one of the vectors is not three-dimensional, a :exc:`ValueError` exception is raised.
.. method:: dot(vector)
Compute the dot product of two vectors.
- .. method:: __eq__(vector)
-
- Test whether two vectors are equal.
-
- .. method:: __mul__(value)
-
- Multiply the vector by a scalar value and return the resulting vector.
-
- .. method:: __truediv__(value)
-
- Divide the vector by a scalar value and return the resulting vector.
-
.. method:: norm()
Return the norm of the vector.
.. method:: norm2()
- Return the square norm of the vector.
+ Return the squared norm of the vector.
.. method:: asunit()
projects / linpy.git / blobdiff