/*forms asymmetric matrix with the same lower triangular part*/
inline void asym(double* a,int n){
int i;
gsl_matrix_view av=gsl_matrix_view_array(a,n,n);
for (i=1;i<n;i++){
gsl_vector_view vsup=gsl_matrix_superdiagonal(&av.matrix,i);
gsl_vector_view vsub=gsl_matrix_subdiagonal(&av.matrix,i);
gsl_vector_memcpy(&vsup.vector,&vsub.vector);
gsl_vector_scale(&vsup.vector,-1);
}
gsl_vector_view vsup=gsl_matrix_superdiagonal(&av.matrix,0);
gsl_vector_set_zero(&vsup.vector);
}
Vector Matrix::superdiagonalVector ( const size_t offset ) {
// To circumvent GSL limitation to allow 0-dimensional vectors
// This use of static data relies on the immutability of 0-dim Vectors.
static Vector nullDimVector( 0, NULL, 0 );
if ( 0 == countRows() ) return nullDimVector;
return Vector( gsl_matrix_superdiagonal( &matrix, offset ) );
}
int
gsl_multifit_linear_Lk(const size_t p, const size_t k, gsl_matrix *L)
{
if (p <= k)
{
GSL_ERROR("p must be larger than derivative order", GSL_EBADLEN);
}
else if (k >= GSL_MULTIFIT_MAXK - 1)
{
GSL_ERROR("derivative order k too large", GSL_EBADLEN);
}
else if (p - k != L->size1 || p != L->size2)
{
GSL_ERROR("L matrix must be (p-k)-by-p", GSL_EBADLEN);
}
else
{
double c_data[GSL_MULTIFIT_MAXK];
gsl_vector_view cv = gsl_vector_view_array(c_data, k + 1);
size_t i, j;
/* zeroth derivative */
if (k == 0)
{
gsl_matrix_set_identity(L);
return GSL_SUCCESS;
}
gsl_matrix_set_zero(L);
gsl_vector_set_zero(&cv.vector);
gsl_vector_set(&cv.vector, 0, -1.0);
gsl_vector_set(&cv.vector, 1, 1.0);
for (i = 1; i < k; ++i)
{
double cjm1 = 0.0;
for (j = 0; j < k + 1; ++j)
{
double cj = gsl_vector_get(&cv.vector, j);
gsl_vector_set(&cv.vector, j, cjm1 - cj);
cjm1 = cj;
}
}
/* build L, the c_i are the entries on the diagonals */
for (i = 0; i < k + 1; ++i)
{
gsl_vector_view v = gsl_matrix_superdiagonal(L, i);
double ci = gsl_vector_get(&cv.vector, i);
gsl_vector_set_all(&v.vector, ci);
}
return GSL_SUCCESS;
}
} /* gsl_multifit_linear_Lk() */