/**
* Description not yet available.
* \param
*/
dvar_vector sfabs(const dvar_vector& t1)
{
RETURN_ARRAYS_INCREMENT();
dvar_vector tmp(t1.indexmin(),t1.indexmax());
for (int i=t1.indexmin(); i<=t1.indexmax(); i++)
{
tmp.elem(i)=sfabs(t1.elem(i));
}
RETURN_ARRAYS_DECREMENT();
return(tmp);
}
/** LU decomposition back susbstitution alogrithm for variable object.
\param a A dmatrix containing LU decomposition of input matrix. \f$a\f$.
\param indx Permutation vector from ludcmp.
\param b A dvector containing the RHS, \f$b\f$ of the linear equation
\f$A\cdot X = B\f$, to be solved, and containing on return the solution vector \f$X\f$.
\n\n The implementation of this algorithm was inspired by
"Numerical Recipes in C", 2nd edition,
Press, Teukolsky, Vetterling, Flannery, chapter 2
*/
void lubksb(dvar_matrix a, const ivector& indx,dvar_vector b)
{
int i,ii=0,ip,j,iiflag=0;
dvariable sum;
int lb=a.colmin();
int ub=a.colmax();
for (i=lb;i<=ub;i++)
{
ip=indx(i);
sum=b(ip);
b(ip)=b(i);
if (iiflag)
{
for (j=ii;j<=i-1;j++)
{
sum -= a.elem(i,j)*b.elem(j);
}
}
else if (!ISZERO(value(sum)))
{
ii=i;
iiflag=1;
}
b(i)=sum;
}
for (i=ub;i>=lb;i--)
{
sum=b(i);
for (j=i+1;j<=ub;j++)
{ // !!! remove to show bug
sum -= a.elem(i,j)*b.elem(j);
} // !!! remove to show bug
b.elem(i)=sum/a.elem(i,i);
}
}