/*! @file ssp_blas2.c

 * \brief Sparse BLAS 2, using some dense BLAS 2 operations

 *

 * 

 * -- SuperLU routine (version 3.0) --

 * Univ. of California Berkeley, Xerox Palo Alto Research Center,

 * and Lawrence Berkeley National Lab.

 * October 15, 2003

 * 

 */

/*

 * File name:		ssp_blas2.c

 * Purpose:		Sparse BLAS 2, using some dense BLAS 2 operations.

 */

#include "slu_sdefs.h"

/* 

 * Function prototypes 

 */

void susolve(int, int, float*, float*);

void slsolve(int, int, float*, float*);

void smatvec(int, int, int, float*, float*, float*);

/*! \brief Solves one of the systems of equations A*x = b,   or   A'*x = b

 * 

 * 

 *   Purpose

 *   =======

 *

 *   sp_strsv() solves one of the systems of equations   

 *       A*x = b,   or   A'*x = b,

 *   where b and x are n element vectors and A is a sparse unit , or   

 *   non-unit, upper or lower triangular matrix.   

 *   No test for singularity or near-singularity is included in this   

 *   routine. Such tests must be performed before calling this routine.   

 *

 *   Parameters   

 *   ==========   

 *

 *   uplo   - (input) char*

 *            On entry, uplo specifies whether the matrix is an upper or   

 *             lower triangular matrix as follows:   

 *                uplo = 'U' or 'u'   A is an upper triangular matrix.   

 *                uplo = 'L' or 'l'   A is a lower triangular matrix.   

 *

 *   trans  - (input) char*

 *             On entry, trans specifies the equations to be solved as   

 *             follows:   

 *                trans = 'N' or 'n'   A*x = b.   

 *                trans = 'T' or 't'   A'*x = b.

 *                trans = 'C' or 'c'   A'*x = b.   

 *

 *   diag   - (input) char*

 *             On entry, diag specifies whether or not A is unit   

 *             triangular as follows:   

 *                diag = 'U' or 'u'   A is assumed to be unit triangular.   

 *                diag = 'N' or 'n'   A is not assumed to be unit   

 *                                    triangular.   

 *	     

 *   L       - (input) SuperMatrix*

 *	       The factor L from the factorization Pr*A*Pc=L*U. Use

 *             compressed row subscripts storage for supernodes,

 *             i.e., L has types: Stype = SC, Dtype = SLU_S, Mtype = TRLU.

 *

 *   U       - (input) SuperMatrix*

 *	        The factor U from the factorization Pr*A*Pc=L*U.

 *	        U has types: Stype = NC, Dtype = SLU_S, Mtype = TRU.

 *    

 *   x       - (input/output) float*

 *             Before entry, the incremented array X must contain the n   

 *             element right-hand side vector b. On exit, X is overwritten 

 *             with the solution vector x.

 *

 *   info    - (output) int*

 *             If *info = -i, the i-th argument had an illegal value.

 * 

 */

int

sp_strsv(char *uplo, char *trans, char *diag, SuperMatrix *L, 

         SuperMatrix *U, float *x, SuperLUStat_t *stat, int *info)

{

#ifdef _CRAY

    _fcd ftcs1 = _cptofcd("L", strlen("L")),

	 ftcs2 = _cptofcd("N", strlen("N")),

	 ftcs3 = _cptofcd("U", strlen("U"));

#endif

    SCformat *Lstore;

    NCformat *Ustore;

    float   *Lval, *Uval;

    int incx = 1, incy = 1;

    float alpha = 1.0, beta = 1.0;

    int nrow;

    int fsupc, nsupr, nsupc, luptr, istart, irow;

    int i, k, iptr, jcol;

    float *work;

    flops_t solve_ops;

    /* Test the input parameters */

    *info = 0;

    if ( !lsame_(uplo,"L") && !lsame_(uplo, "U") ) *info = -1;

    else if ( !lsame_(trans, "N") && !lsame_(trans, "T") && 

              !lsame_(trans, "C")) *info = -2;

    else if ( !lsame_(diag, "U") && !lsame_(diag, "N") ) *info = -3;

    else if ( L->nrow != L->ncol || L->nrow < 0 ) *info = -4;

    else if ( U->nrow != U->ncol || U->nrow < 0 ) *info = -5;

    if ( *info ) {

	i = -(*info);

	xerbla_("sp_strsv", &i);

	return 0;

    }

    Lstore = L->Store;

    Lval = Lstore->nzval;

    Ustore = U->Store;

    Uval = Ustore->nzval;

    solve_ops = 0;

    if ( !(work = floatCalloc(L->nrow)) )

	ABORT("Malloc fails for work in sp_strsv().");

    if ( lsame_(trans, "N") ) {	/* Form x := inv(A)*x. */

	if ( lsame_(uplo, "L") ) {

	    /* Form x := inv(L)*x */

    	    if ( L->nrow == 0 ) return 0; /* Quick return */

	    for (k = 0; k <= Lstore->nsuper; k++) {

		fsupc = L_FST_SUPC(k);

		istart = L_SUB_START(fsupc);

		nsupr = L_SUB_START(fsupc+1) - istart;

		nsupc = L_FST_SUPC(k+1) - fsupc;

		luptr = L_NZ_START(fsupc);

		nrow = nsupr - nsupc;

	        solve_ops += nsupc * (nsupc - 1);

	        solve_ops += 2 * nrow * nsupc;

		if ( nsupc == 1 ) {

		    for (iptr=istart+1; iptr < L_SUB_START(fsupc+1); ++iptr) {

			irow = L_SUB(iptr);

			++luptr;

			x[irow] -= x[fsupc] * Lval[luptr];

		    }

		} else {

#ifdef USE_VENDOR_BLAS

#ifdef _CRAY

		    STRSV(ftcs1, ftcs2, ftcs3, &nsupc, &Lval[luptr], &nsupr,

		       	&x[fsupc], &incx);

		    SGEMV(ftcs2, &nrow, &nsupc, &alpha, &Lval[luptr+nsupc], 

		       	&nsupr, &x[fsupc], &incx, &beta, &work[0], &incy);

#else

		    strsv_("L", "N", "U", &nsupc, &Lval[luptr], &nsupr,

		       	&x[fsupc], &incx);

		    sgemv_("N", &nrow, &nsupc, &alpha, &Lval[luptr+nsupc], 

		       	&nsupr, &x[fsupc], &incx, &beta, &work[0], &incy);

#endif

#else

		    slsolve ( nsupr, nsupc, &Lval[luptr], &x[fsupc]);

		    smatvec ( nsupr, nsupr-nsupc, nsupc, &Lval[luptr+nsupc],

                             &x[fsupc], &work[0] );

#endif		

		    iptr = istart + nsupc;

		    for (i = 0; i < nrow; ++i, ++iptr) {

			irow = L_SUB(iptr);

			x[irow] -= work[i];	/* Scatter */

			work[i] = 0.0;

		    }

	 	}

	    } /* for k ... */

	} else {

	    /* Form x := inv(U)*x */

	    if ( U->nrow == 0 ) return 0; /* Quick return */

	    for (k = Lstore->nsuper; k >= 0; k--) {

	    	fsupc = L_FST_SUPC(k);

	    	nsupr = L_SUB_START(fsupc+1) - L_SUB_START(fsupc);

	    	nsupc = L_FST_SUPC(k+1) - fsupc;

	    	luptr = L_NZ_START(fsupc);

    	        solve_ops += nsupc * (nsupc + 1);

		if ( nsupc == 1 ) {

		    x[fsupc] /= Lval[luptr];

		    for (i = U_NZ_START(fsupc); i < U_NZ_START(fsupc+1); ++i) {

			irow = U_SUB(i);

			x[irow] -= x[fsupc] * Uval[i];

		    }

		} else {

#ifdef USE_VENDOR_BLAS

#ifdef _CRAY

		    STRSV(ftcs3, ftcs2, ftcs2, &nsupc, &Lval[luptr], &nsupr,

		       &x[fsupc], &incx);

#else

		    strsv_("U", "N", "N", &nsupc, &Lval[luptr], &nsupr,

                           &x[fsupc], &incx);

#endif

#else		

		    susolve ( nsupr, nsupc, &Lval[luptr], &x[fsupc] );

#endif		

		    for (jcol = fsupc; jcol < L_FST_SUPC(k+1); jcol++) {

		        solve_ops += 2*(U_NZ_START(jcol+1) - U_NZ_START(jcol));

		    	for (i = U_NZ_START(jcol); i < U_NZ_START(jcol+1); 

				i++) {

			    irow = U_SUB(i);

			    x[irow] -= x[jcol] * Uval[i];

		    	}

                    }

		}

	    } /* for k ... */

	}

    } else { /* Form x := inv(A')*x */

	if ( lsame_(uplo, "L") ) {

	    /* Form x := inv(L')*x */

    	    if ( L->nrow == 0 ) return 0; /* Quick return */

	    for (k = Lstore->nsuper; k >= 0; --k) {

	    	fsupc = L_FST_SUPC(k);

	    	istart = L_SUB_START(fsupc);

	    	nsupr = L_SUB_START(fsupc+1) - istart;

	    	nsupc = L_FST_SUPC(k+1) - fsupc;

	    	luptr = L_NZ_START(fsupc);

		solve_ops += 2 * (nsupr - nsupc) * nsupc;

		for (jcol = fsupc; jcol < L_FST_SUPC(k+1); jcol++) {

		    iptr = istart + nsupc;

		    for (i = L_NZ_START(jcol) + nsupc; 

				i < L_NZ_START(jcol+1); i++) {

			irow = L_SUB(iptr);

			x[jcol] -= x[irow] * Lval[i];

			iptr++;

		    }

		}

		if ( nsupc > 1 ) {

		    solve_ops += nsupc * (nsupc - 1);

#ifdef _CRAY

                    ftcs1 = _cptofcd("L", strlen("L"));

                    ftcs2 = _cptofcd("T", strlen("T"));

                    ftcs3 = _cptofcd("U", strlen("U"));

		    STRSV(ftcs1, ftcs2, ftcs3, &nsupc, &Lval[luptr], &nsupr,

			&x[fsupc], &incx);

#else

		    strsv_("L", "T", "U", &nsupc, &Lval[luptr], &nsupr,

			&x[fsupc], &incx);

#endif

		}

	    }

	} else {

	    /* Form x := inv(U')*x */

	    if ( U->nrow == 0 ) return 0; /* Quick return */

	    for (k = 0; k <= Lstore->nsuper; k++) {

	    	fsupc = L_FST_SUPC(k);

	    	nsupr = L_SUB_START(fsupc+1) - L_SUB_START(fsupc);

	    	nsupc = L_FST_SUPC(k+1) - fsupc;

	    	luptr = L_NZ_START(fsupc);

		for (jcol = fsupc; jcol < L_FST_SUPC(k+1); jcol++) {

		    solve_ops += 2*(U_NZ_START(jcol+1) - U_NZ_START(jcol));

		    for (i = U_NZ_START(jcol); i < U_NZ_START(jcol+1); i++) {

			irow = U_SUB(i);

			x[jcol] -= x[irow] * Uval[i];

		    }

		}

		solve_ops += nsupc * (nsupc + 1);

		if ( nsupc == 1 ) {

		    x[fsupc] /= Lval[luptr];

		} else {

#ifdef _CRAY

                    ftcs1 = _cptofcd("U", strlen("U"));

                    ftcs2 = _cptofcd("T", strlen("T"));

                    ftcs3 = _cptofcd("N", strlen("N"));

		    STRSV( ftcs1, ftcs2, ftcs3, &nsupc, &Lval[luptr], &nsupr,

			    &x[fsupc], &incx);

#else

		    strsv_("U", "T", "N", &nsupc, &Lval[luptr], &nsupr,

			    &x[fsupc], &incx);

#endif

		}

	    } /* for k ... */

	}

    }

    stat->ops[SOLVE] += solve_ops;

    SUPERLU_FREE(work);

    return 0;

}

/*! \brief Performs one of the matrix-vector operations y := alpha*A*x + beta*y,   or   y := alpha*A'*x + beta*y,   

 *

 * 

 *   Purpose   

 *   =======   

 *

 *   sp_sgemv()  performs one of the matrix-vector operations   

 *      y := alpha*A*x + beta*y,   or   y := alpha*A'*x + beta*y,   

 *   where alpha and beta are scalars, x and y are vectors and A is a

 *   sparse A->nrow by A->ncol matrix.   

 *

 *   Parameters   

 *   ==========   

 *

 *   TRANS  - (input) char*

 *            On entry, TRANS specifies the operation to be performed as   

 *            follows:   

 *               TRANS = 'N' or 'n'   y := alpha*A*x + beta*y.   

 *               TRANS = 'T' or 't'   y := alpha*A'*x + beta*y.   

 *               TRANS = 'C' or 'c'   y := alpha*A'*x + beta*y.   

 *

 *   ALPHA  - (input) float

 *            On entry, ALPHA specifies the scalar alpha.   

 *

 *   A      - (input) SuperMatrix*

 *            Matrix A with a sparse format, of dimension (A->nrow, A->ncol).

 *            Currently, the type of A can be:

 *                Stype = NC or NCP; Dtype = SLU_S; Mtype = GE. 

 *            In the future, more general A can be handled.

 *

 *   X      - (input) float*, array of DIMENSION at least   

 *            ( 1 + ( n - 1 )*abs( INCX ) ) when TRANS = 'N' or 'n'   

 *            and at least   

 *            ( 1 + ( m - 1 )*abs( INCX ) ) otherwise.   

 *            Before entry, the incremented array X must contain the   

 *            vector x.   

 *

 *   INCX   - (input) int

 *            On entry, INCX specifies the increment for the elements of   

 *            X. INCX must not be zero.   

 *

 *   BETA   - (input) float

 *            On entry, BETA specifies the scalar beta. When BETA is   

 *            supplied as zero then Y need not be set on input.   

 *

 *   Y      - (output) float*,  array of DIMENSION at least   

 *            ( 1 + ( m - 1 )*abs( INCY ) ) when TRANS = 'N' or 'n'   

 *            and at least   

 *            ( 1 + ( n - 1 )*abs( INCY ) ) otherwise.   

 *            Before entry with BETA non-zero, the incremented array Y   

 *            must contain the vector y. On exit, Y is overwritten by the 

 *            updated vector y.

 *	     

 *   INCY   - (input) int

 *            On entry, INCY specifies the increment for the elements of   

 *            Y. INCY must not be zero.   

 *

 *   ==== Sparse Level 2 Blas routine.   

 * 

 */

int

sp_sgemv(char *trans, float alpha, SuperMatrix *A, float *x, 

	 int incx, float beta, float *y, int incy)

{

    /* Local variables */

    NCformat *Astore;

    float   *Aval;

    int info;

    float temp;

    int lenx, leny, i, j, irow;

    int iy, jx, jy, kx, ky;

    int notran;

    notran = lsame_(trans, "N");

    Astore = A->Store;

    Aval = Astore->nzval;

    /* Test the input parameters */

    info = 0;

    if ( !notran && !lsame_(trans, "T") && !lsame_(trans, "C")) info = 1;

    else if ( A->nrow < 0 || A->ncol < 0 ) info = 3;

    else if (incx == 0) info = 5;

    else if (incy == 0)	info = 8;

    if (info != 0) {

	xerbla_("sp_sgemv ", &info);

	return 0;

    }

    /* Quick return if possible. */

    if (A->nrow == 0 || A->ncol == 0 || (alpha == 0. && beta == 1.))

	return 0;

    /* Set  LENX  and  LENY, the lengths of the vectors x and y, and set 

       up the start points in  X  and  Y. */

    if (lsame_(trans, "N")) {

	lenx = A->ncol;

	leny = A->nrow;

    } else {

	lenx = A->nrow;

	leny = A->ncol;

    }

    if (incx > 0) kx = 0;

    else kx =  - (lenx - 1) * incx;

    if (incy > 0) ky = 0;

    else ky =  - (leny - 1) * incy;

    /* Start the operations. In this version the elements of A are   

       accessed sequentially with one pass through A. */

    /* First form  y := beta*y. */

    if (beta != 1.) {

	if (incy == 1) {

	    if (beta == 0.)

		for (i = 0; i < leny; ++i) y[i] = 0.;

	    else

		for (i = 0; i < leny; ++i) y[i] = beta * y[i];

	} else {

	    iy = ky;

	    if (beta == 0.)

		for (i = 0; i < leny; ++i) {

		    y[iy] = 0.;

		    iy += incy;

		}

	    else

		for (i = 0; i < leny; ++i) {

		    y[iy] = beta * y[iy];

		    iy += incy;

		}

	}

    }

    if (alpha == 0.) return 0;

    if ( notran ) {

	/* Form  y := alpha*A*x + y. */

	jx = kx;

	if (incy == 1) {

	    for (j = 0; j < A->ncol; ++j) {

		if (x[jx] != 0.) {

		    temp = alpha * x[jx];

		    for (i = Astore->colptr[j]; i < Astore->colptr[j+1]; ++i) {

			irow = Astore->rowind[i];

			y[irow] += temp * Aval[i];

		    }

		}

		jx += incx;

	    }

	} else {

	    ABORT("Not implemented.");

	}

    } else {

	/* Form  y := alpha*A'*x + y. */

	jy = ky;

	if (incx == 1) {

	    for (j = 0; j < A->ncol; ++j) {

		temp = 0.;

		for (i = Astore->colptr[j]; i < Astore->colptr[j+1]; ++i) {

		    irow = Astore->rowind[i];

		    temp += Aval[i] * x[irow];

		}

		y[jy] += alpha * temp;

		jy += incy;

	    }

	} else {

	    ABORT("Not implemented.");

	}

    }

    return 0;

} /* sp_sgemv */