/* Ergo, version 3.8, a program for linear scaling electronic structure
 * calculations.
 * Copyright (C) 2019 Elias Rudberg, Emanuel H. Rubensson, Pawel Salek,
 * and Anastasia Kruchinina.
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * Primary academic reference:
 * Ergo: An open-source program for linear-scaling electronic structure
 * calculations,
 * Elias Rudberg, Emanuel H. Rubensson, Pawel Salek, and Anastasia
 * Kruchinina,
 * SoftwareX 7, 107 (2018),
 * <http://dx.doi.org/10.1016/j.softx.2018.03.005>
 * 
 * For further information about Ergo, see <http://www.ergoscf.org>.
 */
 
 /* This file belongs to the template_lapack part of the Ergo source 
  * code. The source files in the template_lapack directory are modified
  * versions of files originally distributed as CLAPACK, see the
  * Copyright/license notice in the file template_lapack/COPYING.
  */
 

#ifndef TEMPLATE_BLAS_TPSV_HEADER
#define TEMPLATE_BLAS_TPSV_HEADER


template<class Treal>
int template_blas_tpsv(const char *uplo, const char *trans, const char *diag, const integer *n, 
	const Treal *ap, Treal *x, const integer *incx)
{
    /* System generated locals */
    integer i__1, i__2;
    /* Local variables */
     integer info;
     Treal temp;
     integer i__, j, k;
     integer kk, ix, jx, kx;
     logical nounit;
/*  Purpose   
    =======   
    DTPSV  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 an n by n unit, or   
    non-unit, upper or lower triangular matrix, supplied in packed form.   
    No test for singularity or near-singularity is included in this   
    routine. Such tests must be performed before calling this routine.   
    Parameters   
    ==========   
    UPLO   - CHARACTER*1.   
             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.   
             Unchanged on exit.   
    TRANS  - CHARACTER*1.   
             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.   
             Unchanged on exit.   
    DIAG   - CHARACTER*1.   
             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.   
             Unchanged on exit.   
    N      - INTEGER.   
             On entry, N specifies the order of the matrix A.   
             N must be at least zero.   
             Unchanged on exit.   
    AP     - DOUBLE PRECISION array of DIMENSION at least   
             ( ( n*( n + 1 ) )/2 ).   
             Before entry with  UPLO = 'U' or 'u', the array AP must   
             contain the upper triangular matrix packed sequentially,   
             column by column, so that AP( 1 ) contains a( 1, 1 ),   
             AP( 2 ) and AP( 3 ) contain a( 1, 2 ) and a( 2, 2 )   
             respectively, and so on.   
             Before entry with UPLO = 'L' or 'l', the array AP must   
             contain the lower triangular matrix packed sequentially,   
             column by column, so that AP( 1 ) contains a( 1, 1 ),   
             AP( 2 ) and AP( 3 ) contain a( 2, 1 ) and a( 3, 1 )   
             respectively, and so on.   
             Note that when  DIAG = 'U' or 'u', the diagonal elements of   
             A are not referenced, but are assumed to be unity.   
             Unchanged on exit.   
    X      - DOUBLE PRECISION array of dimension at least   
             ( 1 + ( n - 1 )*abs( INCX ) ).   
             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.   
    INCX   - INTEGER.   
             On entry, INCX specifies the increment for the elements of   
             X. INCX must not be zero.   
             Unchanged on exit.   
    Level 2 Blas routine.   
    -- Written on 22-October-1986.   
       Jack Dongarra, Argonne National Lab.   
       Jeremy Du Croz, Nag Central Office.   
       Sven Hammarling, Nag Central Office.   
       Richard Hanson, Sandia National Labs.   
       Test the input parameters.   
       Parameter adjustments */
    --x;
    --ap;
    /* Initialization added by Elias to get rid of compiler warnings. */
    kx = 0;
    /* Function Body */
    info = 0;
    if (! template_blas_lsame(uplo, "U") && ! template_blas_lsame(uplo, "L")) {
	info = 1;
    } else if (! template_blas_lsame(trans, "N") && ! template_blas_lsame(trans, 
	    "T") && ! template_blas_lsame(trans, "C")) {
	info = 2;
    } else if (! template_blas_lsame(diag, "U") && ! template_blas_lsame(diag, 
	    "N")) {
	info = 3;
    } else if (*n < 0) {
	info = 4;
    } else if (*incx == 0) {
	info = 7;
    }
    if (info != 0) {
	template_blas_erbla("DTPSV ", &info);
	return 0;
    }
/*     Quick return if possible. */
    if (*n == 0) {
	return 0;
    }
    nounit = template_blas_lsame(diag, "N");
/*     Set up the start point in X if the increment is not unity. This   
       will be  ( N - 1 )*INCX  too small for descending loops. */
    if (*incx <= 0) {
	kx = 1 - (*n - 1) * *incx;
    } else if (*incx != 1) {
	kx = 1;
    }
/*     Start the operations. In this version the elements of AP are   
       accessed sequentially with one pass through AP. */
    if (template_blas_lsame(trans, "N")) {
/*        Form  x := inv( A )*x. */
	if (template_blas_lsame(uplo, "U")) {
	    kk = *n * (*n + 1) / 2;
	    if (*incx == 1) {
		for (j = *n; j >= 1; --j) {
		    if (x[j] != 0.) {
			if (nounit) {
			    x[j] /= ap[kk];
			}
			temp = x[j];
			k = kk - 1;
			for (i__ = j - 1; i__ >= 1; --i__) {
			    x[i__] -= temp * ap[k];
			    --k;
/* L10: */
			}
		    }
		    kk -= j;
/* L20: */
		}
	    } else {
		jx = kx + (*n - 1) * *incx;
		for (j = *n; j >= 1; --j) {
		    if (x[jx] != 0.) {
			if (nounit) {
			    x[jx] /= ap[kk];
			}
			temp = x[jx];
			ix = jx;
			i__1 = kk - j + 1;
			for (k = kk - 1; k >= i__1; --k) {
			    ix -= *incx;
			    x[ix] -= temp * ap[k];
/* L30: */
			}
		    }
		    jx -= *incx;
		    kk -= j;
/* L40: */
		}
	    }
	} else {
	    kk = 1;
	    if (*incx == 1) {
		i__1 = *n;
		for (j = 1; j <= i__1; ++j) {
		    if (x[j] != 0.) {
			if (nounit) {
			    x[j] /= ap[kk];
			}
			temp = x[j];
			k = kk + 1;
			i__2 = *n;
			for (i__ = j + 1; i__ <= i__2; ++i__) {
			    x[i__] -= temp * ap[k];
			    ++k;
/* L50: */
			}
		    }
		    kk += *n - j + 1;
/* L60: */
		}
	    } else {
		jx = kx;
		i__1 = *n;
		for (j = 1; j <= i__1; ++j) {
		    if (x[jx] != 0.) {
			if (nounit) {
			    x[jx] /= ap[kk];
			}
			temp = x[jx];
			ix = jx;
			i__2 = kk + *n - j;
			for (k = kk + 1; k <= i__2; ++k) {
			    ix += *incx;
			    x[ix] -= temp * ap[k];
/* L70: */
			}
		    }
		    jx += *incx;
		    kk += *n - j + 1;
/* L80: */
		}
	    }
	}
    } else {
/*        Form  x := inv( A' )*x. */
	if (template_blas_lsame(uplo, "U")) {
	    kk = 1;
	    if (*incx == 1) {
		i__1 = *n;
		for (j = 1; j <= i__1; ++j) {
		    temp = x[j];
		    k = kk;
		    i__2 = j - 1;
		    for (i__ = 1; i__ <= i__2; ++i__) {
			temp -= ap[k] * x[i__];
			++k;
/* L90: */
		    }
		    if (nounit) {
			temp /= ap[kk + j - 1];
		    }
		    x[j] = temp;
		    kk += j;
/* L100: */
		}
	    } else {
		jx = kx;
		i__1 = *n;
		for (j = 1; j <= i__1; ++j) {
		    temp = x[jx];
		    ix = kx;
		    i__2 = kk + j - 2;
		    for (k = kk; k <= i__2; ++k) {
			temp -= ap[k] * x[ix];
			ix += *incx;
/* L110: */
		    }
		    if (nounit) {
			temp /= ap[kk + j - 1];
		    }
		    x[jx] = temp;
		    jx += *incx;
		    kk += j;
/* L120: */
		}
	    }
	} else {
	    kk = *n * (*n + 1) / 2;
	    if (*incx == 1) {
		for (j = *n; j >= 1; --j) {
		    temp = x[j];
		    k = kk;
		    i__1 = j + 1;
		    for (i__ = *n; i__ >= i__1; --i__) {
			temp -= ap[k] * x[i__];
			--k;
/* L130: */
		    }
		    if (nounit) {
			temp /= ap[kk - *n + j];
		    }
		    x[j] = temp;
		    kk -= *n - j + 1;
/* L140: */
		}
	    } else {
		kx += (*n - 1) * *incx;
		jx = kx;
		for (j = *n; j >= 1; --j) {
		    temp = x[jx];
		    ix = kx;
		    i__1 = kk - (*n - (j + 1));
		    for (k = kk; k >= i__1; --k) {
			temp -= ap[k] * x[ix];
			ix -= *incx;
/* L150: */
		    }
		    if (nounit) {
			temp /= ap[kk - *n + j];
		    }
		    x[jx] = temp;
		    jx -= *incx;
		    kk -= *n - j + 1;
/* L160: */
		}
	    }
	}
    }
    return 0;
/*     End of DTPSV . */
} /* dtpsv_ */

#endif