Table of Contents

Class RobustDeterminant

Namespace
NetTopologySuite.Algorithm
Assembly
NetTopologySuite.dll

Implements an algorithm to compute the sign of a 2x2 determinant for double precision values robustly. It is a direct translation of code developed by Olivier Devillers.

The original code carries the following copyright notice:

Author : Olivier Devillers Olivier.Devillers@sophia.inria.fr http:/www.inria.fr:/prisme/personnel/devillers/anglais/determinant.html

Olivier Devillers has allowed the code to be distributed under the LGPL (2012-02-16) saying "It is ok for LGPL distribution."

Copyright (c) 1995 by INRIA Prisme Project BP 93 06902 Sophia Antipolis Cedex, France. All rights reserved

public class RobustDeterminant
Inheritance
RobustDeterminant
Inherited Members

Constructors

RobustDeterminant() 

public RobustDeterminant()

Methods

OrientationIndex(Coordinate, Coordinate, Coordinate)

Returns the index of the direction of the point q relative to a vector specified by p1-p2.

public static int OrientationIndex(Coordinate p1, Coordinate p2, Coordinate q)

Parameters

p1 Coordinate

The origin point of the vector

p2 Coordinate

The final point of the vector

q Coordinate

the point to compute the direction to

Returns

int
  • 1 if q is counter-clockwise (left) from p1-p2
  • -1 if q is clockwise (right) from p1-p2
  • 0 if q is collinear with p1-p2

SignOfDet2x2(double, double, double, double)

Computes the sign of the determinant of the 2x2 matrix with the given entries, in a robust way.

public static int SignOfDet2x2(double x1, double y1, double x2, double y2)

Parameters

x1 double
y1 double
x2 double
y2 double

Returns

int
  • -1 if the determinant is negative,
  • 1 if the determinant is positive,
  • 0 if the determinant is null.