/* -*- mode: C++; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
// vim:sts=8:sw=8:ts=8:noet:sr:cino=>s,f0,{0,g0,(0,\:0,t0,+0,=s

/* fflas/fflas_ftrsv.inl
 * Copyright (C) 2005 Clement Pernet
 *
 * Written by Clement Pernet <Clement.Pernet@imag.fr>
 *
 * 
 * ========LICENCE========
 * This file is part of the library FFLAS-FFPACK.
 * 
 * FFLAS-FFPACK is free software: you can redistribute it and/or modify
 * it under the terms of the  GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * ========LICENCE========
 *.
 */
#ifndef __FFLASFFPACK_ftrsv_INL
#define __FFLASFFPACK_ftrsv_INL

namespace FFLAS {
//---------------------------------------------------------------------
// ftrsv: TRiangular System solve with vector
// Computes  X <- op(A^-1).X
// size of X is m
//---------------------------------------------------------------------
template<class Field>
inline void
ftrsv (const Field& F, const FFLAS_UPLO Uplo,
	      const FFLAS_TRANSPOSE TransA, const FFLAS_DIAG Diag,
	      const size_t N,const typename Field::Element * A, size_t lda,
	      typename Field::Element * X, int incX)
{

	typename Field::Element * Xi,* Xj, * Ximax;
	const typename Field::Element * Ai, * Aj;
	if ( Uplo == FflasLower ){
		if ( TransA == FflasTrans){
			Ai = A+(N-1)*(lda+1); // bottom right entry of A
			Ximax = Xi = X+(N-1)*incX;
			for( ; Xi>=X; Ai-=lda+1,Xi-=incX ){
				F.negin( *Xi );
				for ( Xj = Xi+incX, Aj=Ai+lda; Xj<=Ximax;
				      Xj+=incX, Aj+=lda){
					F.axpyin( *Xi, *Xj, *Aj );
				}
				if ( Diag==FflasNonUnit ){
					F.divin(*Xi,*Ai);
				}
				F.negin( *Xi );
			}
		} // FflasTrans
		else{
			Ai = A;
		        Xi = X;
			for( ; Xi<X+incX*N; Ai+=lda+1,Xi+=incX ){
				F.negin( *Xi );
				for ( Xj = Xi-incX, Aj=Ai-1; Xj>=X;
				      Xj-=incX, Aj--){
					F.axpyin( *Xi, *Xj, *Aj );
				}
				if ( Diag==FflasNonUnit )
					F.divin(*Xi,*Ai);
				F.negin( *Xi );
			}
		}
	} // FflasLower
	else{
		if ( TransA == FflasTrans){
			Ai = A;
			Xi = X;
			for( ; Xi<X+N*incX; Ai+=lda+1,Xi+=incX ){
				F.negin( *Xi );
				for ( Xj = Xi-incX, Aj=Ai-lda; Xj>=X;
				      Xj-=incX, Aj-=lda){
					F.axpyin( *Xi, *Xj, *Aj );
				}

				if ( Diag==FflasNonUnit )
					F.divin(*Xi,*Ai);
				F.negin( *Xi );
			}

		} // FflasTrans
		else{
			Ai = A+(lda+1)*(N-1);
			Ximax = Xi = X+incX*(N-1);
			for( ; Xi>=X; Ai-=lda+1,Xi-=incX ){
				F.negin( *Xi );
				for ( Xj = Xi+incX, Aj=Ai+1; Xj<=Ximax;
				      Xj+=incX, Aj++){
					F.axpyin( *Xi, *Xj, *Aj );
				}
				if ( Diag==FflasNonUnit )
					F.divin(*Xi,*Ai);
				F.negin( *Xi );
			}
		}
	}
}

}

#endif // __FFLASFFPACK_ftrsv_INL
