#include "blaswrap.h"
#ifdef _cpluscplus
extern "C" {
#endif
#include "f2c.h"

/* Subroutine */ int dtpmv_(char *uplo, char *trans, char *diag, integer *n, 
	doublereal *ap, doublereal *x, integer *incx)
{
    /* System generated locals */
    integer i__1, i__2;
    /* Local variables */
    static integer info;
    static doublereal temp;
    static integer i__, j, k;
    extern logical lsame_(char *, char *);
    static integer kk, ix, jx, kx;
    extern /* Subroutine */ int xerbla_(char *, integer *);
    static logical nounit;
/*  Purpose   
    =======   
    DTPMV  performs one of the matrix-vector operations   
       x := A*x,   or   x := A'*x,   
    where x is an n element vector and  A is an n by n unit, or non-unit,   
    upper or lower triangular matrix, supplied in packed form.   
    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 operation to be performed as   
             follows:   
                TRANS = 'N' or 'n'   x := A*x.   
                TRANS = 'T' or 't'   x := A'*x.   
                TRANS = 'C' or 'c'   x := A'*x.   
             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 vector x. On exit, X is overwritten with the   
             tranformed 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;
    /* Function Body */
    info = 0;
    if (! lsame_(uplo, "U") && ! lsame_(uplo, "L")) {
	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 (*n < 0) {
	info = 4;
    } else if (*incx == 0) {
	info = 7;
    }
    if (info != 0) {
	xerbla_("DTPMV ", &info);
	return 0;
    }
/*     Quick return if possible. */
    if (*n == 0) {
	return 0;
    }
    nounit = 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 (lsame_(trans, "N")) {
/*        Form  x:= A*x. */
	if (lsame_(uplo, "U")) {
	    kk = 1;
	    if (*incx == 1) {
		i__1 = *n;
		for (j = 1; j <= i__1; ++j) {
		    if (x[j] != 0.) {
			temp = x[j];
			k = kk;
			i__2 = j - 1;
			for (i__ = 1; i__ <= i__2; ++i__) {
			    x[i__] += temp * ap[k];
			    ++k;
/* L10: */
			}
			if (nounit) {
			    x[j] *= ap[kk + j - 1];
			}
		    }
		    kk += j;
/* L20: */
		}
	    } else {
		jx = kx;
		i__1 = *n;
		for (j = 1; j <= i__1; ++j) {
		    if (x[jx] != 0.) {
			temp = x[jx];
			ix = kx;
			i__2 = kk + j - 2;
			for (k = kk; k <= i__2; ++k) {
			    x[ix] += temp * ap[k];
			    ix += *incx;
/* L30: */
			}
			if (nounit) {
			    x[jx] *= ap[kk + j - 1];
			}
		    }
		    jx += *incx;
		    kk += j;
/* L40: */
		}
	    }
	} else {
	    kk = *n * (*n + 1) / 2;
	    if (*incx == 1) {
		for (j = *n; j >= 1; --j) {
		    if (x[j] != 0.) {
			temp = x[j];
			k = kk;
			i__1 = j + 1;
			for (i__ = *n; i__ >= i__1; --i__) {
			    x[i__] += temp * ap[k];
			    --k;
/* L50: */
			}
			if (nounit) {
			    x[j] *= ap[kk - *n + j];
			}
		    }
		    kk -= *n - j + 1;
/* L60: */
		}
	    } else {
		kx += (*n - 1) * *incx;
		jx = kx;
		for (j = *n; j >= 1; --j) {
		    if (x[jx] != 0.) {
			temp = x[jx];
			ix = kx;
			i__1 = kk - (*n - (j + 1));
			for (k = kk; k >= i__1; --k) {
			    x[ix] += temp * ap[k];
			    ix -= *incx;
/* L70: */
			}
			if (nounit) {
			    x[jx] *= ap[kk - *n + j];
			}
		    }
		    jx -= *incx;
		    kk -= *n - j + 1;
/* L80: */
		}
	    }
	}
    } else {
/*        Form  x := A'*x. */
	if (lsame_(uplo, "U")) {
	    kk = *n * (*n + 1) / 2;
	    if (*incx == 1) {
		for (j = *n; j >= 1; --j) {
		    temp = x[j];
		    if (nounit) {
			temp *= ap[kk];
		    }
		    k = kk - 1;
		    for (i__ = j - 1; i__ >= 1; --i__) {
			temp += ap[k] * x[i__];
			--k;
/* L90: */
		    }
		    x[j] = temp;
		    kk -= j;
/* L100: */
		}
	    } else {
		jx = kx + (*n - 1) * *incx;
		for (j = *n; j >= 1; --j) {
		    temp = x[jx];
		    ix = jx;
		    if (nounit) {
			temp *= ap[kk];
		    }
		    i__1 = kk - j + 1;
		    for (k = kk - 1; k >= i__1; --k) {
			ix -= *incx;
			temp += ap[k] * x[ix];
/* L110: */
		    }
		    x[jx] = temp;
		    jx -= *incx;
		    kk -= j;
/* L120: */
		}
	    }
	} else {
	    kk = 1;
	    if (*incx == 1) {
		i__1 = *n;
		for (j = 1; j <= i__1; ++j) {
		    temp = x[j];
		    if (nounit) {
			temp *= ap[kk];
		    }
		    k = kk + 1;
		    i__2 = *n;
		    for (i__ = j + 1; i__ <= i__2; ++i__) {
			temp += ap[k] * x[i__];
			++k;
/* L130: */
		    }
		    x[j] = temp;
		    kk += *n - j + 1;
/* L140: */
		}
	    } else {
		jx = kx;
		i__1 = *n;
		for (j = 1; j <= i__1; ++j) {
		    temp = x[jx];
		    ix = jx;
		    if (nounit) {
			temp *= ap[kk];
		    }
		    i__2 = kk + *n - j;
		    for (k = kk + 1; k <= i__2; ++k) {
			ix += *incx;
			temp += ap[k] * x[ix];
/* L150: */
		    }
		    x[jx] = temp;
		    jx += *incx;
		    kk += *n - j + 1;
/* L160: */
		}
	    }
	}
    }
    return 0;
/*     End of DTPMV . */
} /* dtpmv_ */

#ifdef _cpluscplus
}
#endif
