Invert< 3 > Class Reference

#include <Dinv.hh>

Static Public Member Functions
template<class Matrix >
static bool	Dinv (Matrix &rhs)

Detailed Description

Invert<3>. $3\times3$ (sub-)matrix. Use pivotisation.

Author

T. Glebe

Member Function Documentation

Dinv()

template<class Matrix >

static bool Invert< 3 >::Dinv ( Matrix &  rhs )

inlinestatic

                                {
 
    typename Matrix::value_type* a = rhs.Array();
 
    static typename Matrix::value_type t1, t2, t3, temp, s;
    static typename Matrix::value_type c11, c12, c13, c21, c22, c23, c31, c32, c33, det;
 
  
    /*     COMPUTE COFACTORS. */
    c11 = a[4] * a[8] - a[7] * a[5];
    c12 = a[7] * a[2] - a[1] * a[8];
    c13 = a[1] * a[5] - a[4] * a[2];
    c21 = a[5] * a[6] - a[8] * a[3];
    c22 = a[8] * a[0] - a[2] * a[6];
    c23 = a[2] * a[3] - a[5] * a[0];
    c31 = a[3] * a[7] - a[6] * a[4];
    c32 = a[6] * a[1] - a[0] * a[7];
    c33 = a[0] * a[4] - a[3] * a[1];
 
    t1 = fabs(a[0]);
    t2 = fabs(a[1]);
    t3 = fabs(a[2]);
    
    /*     (SET TEMP=PIVOT AND DET=PIVOT*DET.) */
    if(t1 < t2) {
      if (t3 < t2) {
    /*        (PIVOT IS A21) */
    temp = a[1];
    det = c13 * c32 - c12 * c33;
      } else {
    /*     (PIVOT IS A31) */
    temp = a[2];
    det = c23 * c12 - c22 * c13;
      }
    } else {
      if(t3 < t1) {
    /*     (PIVOT IS A11) */
    temp = a[0];
    det = c22 * c33 - c23 * c32;
      } else {
    /*     (PIVOT IS A31) */
    temp = a[2];
    det = c23 * c12 - c22 * c13;
      }
    }
 
    if (det == 0.) {
      return false;
    }
 
    /*     SET ELEMENTS OF INVERSE IN A. */
    s = temp / det;
    a[0] = s * c11;
    a[3] = s * c21;
    a[6] = s * c31;
    a[1] = s * c12;
    a[4] = s * c22;
    a[7] = s * c32;
    a[2] = s * c13;
    a[5] = s * c23;
    a[8] = s * c33;
    return true;
  }

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The documentation for this class was generated from the following file:

• src/libVt++/smatrix/include/Dinv.hh