Function applyreflectionfromtheleft

src/reflections.cpp:188–228

Application of an elementary reflection to a rectangular matrix of size MxN The algorithm pre-multiplies the matrix by an elementary reflection transformation which is given by column V and scalar Tau (see the description of the GenerateReflection procedure). Not the whole matrix but only a part of it is transformed (rows from M1 to M2, columns from N1 to N2). Only the elements of this submatrix

     September 30, 1994
*************************************************************************/
void applyreflectionfromtheleft(ap::real_2d_array& c,
     double tau,
     const ap::real_1d_array& v,
     int m1,
     int m2,
     int n1,
     int n2,
     ap::real_1d_array& work)
{
    double t;
    int i;
    int vm;

    if( ap::fp_eq(tau,0)||n1>n2||m1>m2 )
    {
        return;
    }
    
    //
    // w := C' * v
    //
    vm = m2-m1+1;
    for(i = n1; i <= n2; i++)
    {
        work(i) = 0;
    }
    for(i = m1; i <= m2; i++)
    {
        t = v(i+1-m1);
        ap::vadd(&work(n1), 1, &c(i, n1), 1, ap::vlen(n1,n2), t);
    }
    
    //
    // C := C - tau * v * w'
    //
    for(i = m1; i <= m2; i++)
    {
        t = v(i-m1+1)*tau;
        ap::vsub(&c(i, n1), 1, &work(n1), 1, ap::vlen(n1,n2), t);
    }
}


/*************************************************************************