Geogram  Version 1.9.1
A programming library of geometric algorithms
determinant.h
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39 
40 #ifndef GEOGRAM_BASIC_DETERMINANT
41 #define GEOGRAM_BASIC_DETERMINANT
42 
43 #include <geogram/basic/common.h>
44 
50 namespace GEO {
51 
52  /************************************************************************/
53 
57  template <class T>
58  inline T det2x2(
59  const T& a11, const T& a12,
60  const T& a21, const T& a22
61  ) {
62  return a11*a22-a12*a21 ;
63  }
64 
68  template <class T>
69  inline T det3x3(
70  const T& a11, const T& a12, const T& a13,
71  const T& a21, const T& a22, const T& a23,
72  const T& a31, const T& a32, const T& a33
73  ) {
74  return
75  a11*det2x2(a22,a23,a32,a33)
76  -a21*det2x2(a12,a13,a32,a33)
77  +a31*det2x2(a12,a13,a22,a23);
78  }
79 
80 
84  template <class T>
85  inline T det4x4(
86  const T& a11, const T& a12, const T& a13, const T& a14,
87  const T& a21, const T& a22, const T& a23, const T& a24,
88  const T& a31, const T& a32, const T& a33, const T& a34,
89  const T& a41, const T& a42, const T& a43, const T& a44
90  ) {
91  T m12 = a21*a12 - a11*a22;
92  T m13 = a31*a12 - a11*a32;
93  T m14 = a41*a12 - a11*a42;
94  T m23 = a31*a22 - a21*a32;
95  T m24 = a41*a22 - a21*a42;
96  T m34 = a41*a32 - a31*a42;
97 
98  T m123 = m23*a13 - m13*a23 + m12*a33;
99  T m124 = m24*a13 - m14*a23 + m12*a43;
100  T m134 = m34*a13 - m14*a33 + m13*a43;
101  T m234 = m34*a23 - m24*a33 + m23*a43;
102 
103  return (m234*a14 - m134*a24 + m124*a34 - m123*a44);
104  }
105 }
106 
107 #endif
Common include file, providing basic definitions. Should be included before anything else by all head...
Global Vorpaline namespace.
Definition: basic.h:55
T det3x3(const T &a11, const T &a12, const T &a13, const T &a21, const T &a22, const T &a23, const T &a31, const T &a32, const T &a33)
Computes a three-by-three determinant.
Definition: determinant.h:69
T det4x4(const T &a11, const T &a12, const T &a13, const T &a14, const T &a21, const T &a22, const T &a23, const T &a24, const T &a31, const T &a32, const T &a33, const T &a34, const T &a41, const T &a42, const T &a43, const T &a44)
Computes a four-by-four determinant.
Definition: determinant.h:85
T det2x2(const T &a11, const T &a12, const T &a21, const T &a22)
Computes a two-by-two determinant.
Definition: determinant.h:58