OOF2: The Manual

Coord
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Name

Coord — Coordinate classes

Synopses

C++ Synopsis

#include "common/coord.h"
class Position {
  virtual Coord position() const = 0;
}
class Coord: , public Position {
  Coord();
  Coord(double x,
        double y);
  double operator()(int i) const;
  double& operator()(int i);
  Coord& operator+=(const Coord& other);
  Coord& operator-=(const Coord& other);
  Coord& operator*=(double factor);
  Coord& operator/=(double factor);
}
Coord operator+(const Coord&, const Coord&)
Coord operator-(const Coord&, const Coord&)
Coord operator*(const Coord&, double)
Coord operator((double, const Coord&)
double cross(const Coord&, const Coord&)
double operator%(const Coord&, const Coord&)
double dot(const Coord&, const Coord&)
double norm2(const Coord&)

bool operator<(const Coord&, const Coord&);
bool operator==(const Coord&, const Coord&);
bool operator!=(const Coord&, const Coord&);

Python Synopsis

from oof2.SWIG.common import coord
class Position:
   pass
class Coord(Position):
  def __getitem__(self, i)
  def __mul__(self, factor)
  def __rmul__(self, factor)
  def __cmp__(self, other)

Source Files

  • SRC/common/coord.C: C++ code
  • SRC/common/coord.h: C++ header file
  • SRC/common/coord.swg: swig code
  • SRC/common/coord.spy: Python code included in swig output

Description

Position and its subclasses, including Coord, represent points on the two dimensional plane of an OOF2 calculation. The other subclass of Position is GaussPoint, which has a lot more machinery attached to it than Coord does. OOF2 extension authors shouldn't have to write code involving GaussPoints explicitly,[67] so that class isn't documented here.

Coord is a C++ class and is not intended for heavy use in Python. It's swigged so that occasional Python operations can be performed, but most of the arithmetic functions are only available in C++. When there's one Coord, there tend to be a lot of them, so if you find yourself doing Coord arithmetic in Python, you should think about doing it in C++ instead.

Methods

virtual Coord position() const

position is the only function in the Position base class. It effectively converts any Position object to a Coord. It's useful when a routine needs to operate on generic Position objects, but still wants to perform arithmetic with them.[68]

Coord(), Coord(double x, double y)

Coord(x,y) creates a Coord at position \((x, y)\), as you'd expect. The default constructor, Coord(0) creates one at \((0, 0)\).

double operator()(int i), __getitem__(i)

These operators retrieve the x and y components of the Coord. The C++ version uses operator() instead of operator[] for historical reasons, for which we apologize. The argument i should be 0 for x and 1 for y.

operator+=, operator*, etc.

The standard arithmetic operations are defined for Coords in C++. As noted above, most of them are not defined in Python.

double cross(const Coord&, const Coord&), double operator%(const Coord&, const Coord&)

The cross product of two Coords a and b can be computed either by cross(a,b) or by a%b. Because Coords are two dimensional vectors, the cross product is a scalar, not a vector. It's equivalent to the z-component of a three dimensional cross product.

double dot(const Coord&, const Coord&)

dot returns the dot product of its arguments.

double norm2(const Coord&)

norm2 returns the square of the norm of its argument. norm2(x) is equivalent to dot(x,x).

operator<, operator==, operator!=, __cmp__

The basic comparison operators are available for Coords in C++ and Python. The C++ operator< and the Python __cmp__ are provided mostly so that Coords can be used as keys in STL maps.


[67] If we've done our job correctly, that is.

[68] GaussPoints, which are derived from Positions, represent special fixed points inside an Element, so it doesn't really make sense to do arithmetic with them. Therefore there are no arithmetic operations defined in the Position base class.

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