Class RobustDeterminant

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

Inheritance
object
RobustDeterminant
Inherited Members
Namespace: NetTopologySuite.Algorithm
Assembly: NetTopologySuite.dll
Syntax
public class RobustDeterminant

Methods

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OrientationIndex(Coordinate, Coordinate, Coordinate)

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

Declaration
public static int OrientationIndex(Coordinate p1, Coordinate p2, Coordinate q)
Parameters
Type Name Description
Coordinate p1

The origin point of the vector
Coordinate p2

The final point of the vector
Coordinate q

the point to compute the direction to
Returns
Type Description
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
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SignOfDet2x2(double, double, double, double)

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

Declaration
public static int SignOfDet2x2(double x1, double y1, double x2, double y2)
Parameters
Type Name Description
double x1
double y1
double x2
double y2
Returns
Type Description
int
  • -1 if the determinant is negative,
  • 1 if the determinant is positive,
  • 0 if the determinant is null.