#include "blaswrap.h"
#include "f2c.h"

/* Subroutine */ int ssymv_(char *uplo, integer *n, real *alpha, real *a, 
	integer *lda, real *x, integer *incx, real *beta, real *y, integer *
	incy)
{
    /* System generated locals */
    integer a_dim1, a_offset, i__1, i__2;
    /* Local variables */
    static integer i__, j, ix, iy, jx, jy, kx, ky, info;
    static real temp1, temp2;
    extern logical lsame_(char *, char *);
    extern /* Subroutine */ int xerbla_(char *, integer *);
/*  Purpose   
    =======   
    SSYMV  performs the matrix-vector  operation   
       y := alpha*A*x + beta*y,   
    where alpha and beta are scalars, x and y are n element vectors and   
    A is an n by n symmetric matrix.   
    Arguments   
    ==========   
    UPLO   - CHARACTER*1.   
             On entry, UPLO specifies whether the upper or lower   
             triangular part of the array A is to be referenced as   
             follows:   
                UPLO = 'U' or 'u'   Only the upper triangular part of A   
                                    is to be referenced.   
                UPLO = 'L' or 'l'   Only the lower triangular part of A   
                                    is to be referenced.   
             Unchanged on exit.   
    N      - INTEGER.   
             On entry, N specifies the order of the matrix A.   
             N must be at least zero.   
             Unchanged on exit.   
    ALPHA  - REAL            .   
             On entry, ALPHA specifies the scalar alpha.   
             Unchanged on exit.   
    A      - REAL             array of DIMENSION ( LDA, n ).   
             Before entry with  UPLO = 'U' or 'u', the leading n by n   
             upper triangular part of the array A must contain the upper   
             triangular part of the symmetric matrix and the strictly   
             lower triangular part of A is not referenced.   
             Before entry with UPLO = 'L' or 'l', the leading n by n   
             lower triangular part of the array A must contain the lower   
             triangular part of the symmetric matrix and the strictly   
             upper triangular part of A is not referenced.   
             Unchanged on exit.   
    LDA    - INTEGER.   
             On entry, LDA specifies the first dimension of A as declared   
             in the calling (sub) program. LDA must be at least   
             max( 1, n ).   
             Unchanged on exit.   
    X      - REAL             array of dimension at least   
             ( 1 + ( n - 1 )*abs( INCX ) ).   
             Before entry, the incremented array X must contain the n   
             element vector x.   
             Unchanged on exit.   
    INCX   - INTEGER.   
             On entry, INCX specifies the increment for the elements of   
             X. INCX must not be zero.   
             Unchanged on exit.   
    BETA   - REAL            .   
             On entry, BETA specifies the scalar beta. When BETA is   
             supplied as zero then Y need not be set on input.   
             Unchanged on exit.   
    Y      - REAL             array of dimension at least   
             ( 1 + ( n - 1 )*abs( INCY ) ).   
             Before entry, the incremented array Y must contain the n   
             element vector y. On exit, Y is overwritten by the updated   
             vector y.   
    INCY   - INTEGER.   
             On entry, INCY specifies the increment for the elements of   
             Y. INCY 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 */
    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    --x;
    --y;
    /* Function Body */
    info = 0;
    if (! lsame_(uplo, "U") && ! lsame_(uplo, "L")) {
	info = 1;
    } else if (*n < 0) {
	info = 2;
    } else if (*lda < max(1,*n)) {
	info = 5;
    } else if (*incx == 0) {
	info = 7;
    } else if (*incy == 0) {
	info = 10;
    }
    if (info != 0) {
	xerbla_("SSYMV ", &info);
	return 0;
    }
/*     Quick return if possible. */
    if (*n == 0 || *alpha == 0.f && *beta == 1.f) {
	return 0;
    }
/*     Set up the start points in  X  and  Y. */
    if (*incx > 0) {
	kx = 1;
    } else {
	kx = 1 - (*n - 1) * *incx;
    }
    if (*incy > 0) {
	ky = 1;
    } else {
	ky = 1 - (*n - 1) * *incy;
    }
/*     Start the operations. In this version the elements of A are   
       accessed sequentially with one pass through the triangular part   
       of A.   
       First form  y := beta*y. */
    if (*beta != 1.f) {
	if (*incy == 1) {
	    if (*beta == 0.f) {
		i__1 = *n;
		for (i__ = 1; i__ <= i__1; ++i__) {
		    y[i__] = 0.f;
/* L10: */
		}
	    } else {
		i__1 = *n;
		for (i__ = 1; i__ <= i__1; ++i__) {
		    y[i__] = *beta * y[i__];
/* L20: */
		}
	    }
	} else {
	    iy = ky;
	    if (*beta == 0.f) {
		i__1 = *n;
		for (i__ = 1; i__ <= i__1; ++i__) {
		    y[iy] = 0.f;
		    iy += *incy;
/* L30: */
		}
	    } else {
		i__1 = *n;
		for (i__ = 1; i__ <= i__1; ++i__) {
		    y[iy] = *beta * y[iy];
		    iy += *incy;
/* L40: */
		}
	    }
	}
    }
    if (*alpha == 0.f) {
	return 0;
    }
    if (lsame_(uplo, "U")) {
/*        Form  y  when A is stored in upper triangle. */
	if (*incx == 1 && *incy == 1) {
	    i__1 = *n;
	    for (j = 1; j <= i__1; ++j) {
		temp1 = *alpha * x[j];
		temp2 = 0.f;
		i__2 = j - 1;
		for (i__ = 1; i__ <= i__2; ++i__) {
		    y[i__] += temp1 * a[i__ + j * a_dim1];
		    temp2 += a[i__ + j * a_dim1] * x[i__];
/* L50: */
		}
		y[j] = y[j] + temp1 * a[j + j * a_dim1] + *alpha * temp2;
/* L60: */
	    }
	} else {
	    jx = kx;
	    jy = ky;
	    i__1 = *n;
	    for (j = 1; j <= i__1; ++j) {
		temp1 = *alpha * x[jx];
		temp2 = 0.f;
		ix = kx;
		iy = ky;
		i__2 = j - 1;
		for (i__ = 1; i__ <= i__2; ++i__) {
		    y[iy] += temp1 * a[i__ + j * a_dim1];
		    temp2 += a[i__ + j * a_dim1] * x[ix];
		    ix += *incx;
		    iy += *incy;
/* L70: */
		}
		y[jy] = y[jy] + temp1 * a[j + j * a_dim1] + *alpha * temp2;
		jx += *incx;
		jy += *incy;
/* L80: */
	    }
	}
    } else {
/*        Form  y  when A is stored in lower triangle. */
	if (*incx == 1 && *incy == 1) {
	    i__1 = *n;
	    for (j = 1; j <= i__1; ++j) {
		temp1 = *alpha * x[j];
		temp2 = 0.f;
		y[j] += temp1 * a[j + j * a_dim1];
		i__2 = *n;
		for (i__ = j + 1; i__ <= i__2; ++i__) {
		    y[i__] += temp1 * a[i__ + j * a_dim1];
		    temp2 += a[i__ + j * a_dim1] * x[i__];
/* L90: */
		}
		y[j] += *alpha * temp2;
/* L100: */
	    }
	} else {
	    jx = kx;
	    jy = ky;
	    i__1 = *n;
	    for (j = 1; j <= i__1; ++j) {
		temp1 = *alpha * x[jx];
		temp2 = 0.f;
		y[jy] += temp1 * a[j + j * a_dim1];
		ix = jx;
		iy = jy;
		i__2 = *n;
		for (i__ = j + 1; i__ <= i__2; ++i__) {
		    ix += *incx;
		    iy += *incy;
		    y[iy] += temp1 * a[i__ + j * a_dim1];
		    temp2 += a[i__ + j * a_dim1] * x[ix];
/* L110: */
		}
		y[jy] += *alpha * temp2;
		jx += *incx;
		jy += *incy;
/* L120: */
	    }
	}
    }
    return 0;
/*     End of SSYMV . */
} /* ssymv_ */