[uplo,n,alpha,x,incx,y,incy,a,lda]=ssyr2(uplo,n,alpha,x,incx,y,incy,a,lda);

function [uplo,n,alpha,x,incx,y,incy,a,lda]=ssyr2(uplo,n,alpha,x,incx,y,incy,a,lda);
%***BEGIN PROLOGUE  SSYR2
%***PURPOSE  Perform symmetric rank 2 update of a real symmetric matrix.
%***LIBRARY   SLATEC (BLAS)
%***CATEGORY  D1B4
%***TYPE      SINGLE PRECISION (SSYR2-S, DSYR2-D, CSYR2-C)
%***KEYWORDS  LEVEL 2 BLAS, LINEAR ALGEBRA
%***AUTHOR  Dongarra, J. J., (ANL)
%           Du Croz, J., (NAG)
%           Hammarling, S., (NAG)
%           Hanson, R. J., (SNLA)
%***DESCRIPTION
%
%  SSYR2  performs the symmetric rank 2 operation
%
%     A := alpha*x*y' + alpha*y*x' + A,
%
%  where alpha is a scalar, x and y are n element vectors and A is an n
%  by n symmetric matrix.
%
%  Parameters
%  ==========
%
%  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.
%
%  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.
%
%  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.
%           Unchanged on exit.
%
%  INCY   - INTEGER.
%           On entry, INCY specifies the increment for the elements of
%           Y. INCY must not be zero.
%           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. On exit, the
%           upper triangular part of the array A is overwritten by the
%           upper triangular part of the updated matrix.
%           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. On exit, the
%           lower triangular part of the array A is overwritten by the
%           lower triangular part of the updated matrix.
%
%  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.
%
%***REFERENCES  Dongarra, J. J., Du Croz, J., Hammarling, S., and
%                 Hanson, R. J.  An extended set of Fortran basic linear
%                 algebra subprograms.  ACM TOMS, Vol. 14, No. 1,
%                 pp. 1-17, March 1988.
%***ROUTINES CALLED  LSAME, XERBLA
%***REVISION HISTORY  (YYMMDD)
%   861022  DATE WRITTEN
%   910605  Modified to meet SLATEC prologue standards.  Only comment
%           lines were modified.  (BKS)
%***end PROLOGUE  SSYR2
%     .. Scalar Arguments ..
%     .. Array Arguments ..
persistent i info ix iy j jx jy kx ky temp1 temp2 zero ; 

a_shape=size(a);a=reshape([a(:).',zeros(1,ceil(numel(a)./prod([lda])).*prod([lda])-numel(a))],lda,[]);
x_shape=size(x);x=reshape(x,1,[]);
y_shape=size(y);y=reshape(y,1,[]);
%     .. Parameters ..
if isempty(zero), zero=0.0e+0 ; end;
%     .. Local Scalars ..
if isempty(temp1), temp1=0; end;
if isempty(temp2), temp2=0; end;
if isempty(i), i=0; end;
if isempty(info), info=0; end;
if isempty(ix), ix=0; end;
if isempty(iy), iy=0; end;
if isempty(j), j=0; end;
if isempty(jx), jx=0; end;
if isempty(jy), jy=0; end;
if isempty(kx), kx=0; end;
if isempty(ky), ky=0; end;
%     .. External Functions ..
%     .. External Subroutines ..
%     .. Intrinsic Functions ..
%***FIRST EXECUTABLE STATEMENT  SSYR2
%
%     Test the input parameters.
%
info = 0;
if( ~lsame(uplo,'U') && ~lsame(uplo,'L') )
info = 1;
elseif( n<0 ) ;
info = 2;
elseif( incx==0 ) ;
info = 5;
elseif( incy==0 ) ;
info = 7;
elseif( lda<max(1,n) ) ;
info = 9;
end;
if( info~=0 )
[dumvar1,info]=xerbla('SSYR2 ',info);
a_shape=zeros(a_shape);a_shape(:)=a(1:numel(a_shape));a=a_shape;
x_shape=zeros(x_shape);x_shape(:)=x(1:numel(x_shape));x=x_shape;
y_shape=zeros(y_shape);y_shape(:)=y(1:numel(y_shape));y=y_shape;
return;
end;
%
%     Quick return if possible.
%
if((n==0) ||(alpha==zero) )
a_shape=zeros(a_shape);a_shape(:)=a(1:numel(a_shape));a=a_shape;
x_shape=zeros(x_shape);x_shape(:)=x(1:numel(x_shape));x=x_shape;
y_shape=zeros(y_shape);y_shape(:)=y(1:numel(y_shape));y=y_shape;
return;
end;
%
%     Set up the start points in X and Y if the increments are not both
%     unity.
%
if((incx~=1) ||(incy~=1) )
if( incx>0 )
kx = 1;
else;
kx = fix(1 -(n-1).*incx);
end;
if( incy>0 )
ky = 1;
else;
ky = fix(1 -(n-1).*incy);
end;
jx = fix(kx);
jy = fix(ky);
end;
%
%     Start the operations. In this version the elements of A are
%     accessed sequentially with one pass through the triangular part
%     of A.
%
if( lsame(uplo,'U') )
%
%        Form  A  when A is stored in the upper triangle.
%
if((incx==1) &&(incy==1) )
for j = 1 : n;
if((x(j)~=zero) ||(y(j)~=zero) )
temp1 = alpha.*y(j);
temp2 = alpha.*x(j);
for i = 1 : j;
a(i,j) = a(i,j) + x(i).*temp1 + y(i).*temp2;
end; i = fix(j+1);
end;
end; j = fix(n+1);
else;
for j = 1 : n;
if((x(jx)~=zero) ||(y(jy)~=zero) )
temp1 = alpha.*y(jy);
temp2 = alpha.*x(jx);
ix = fix(kx);
iy = fix(ky);
for i = 1 : j;
a(i,j) = a(i,j) + x(ix).*temp1 + y(iy).*temp2;
ix = fix(ix + incx);
iy = fix(iy + incy);
end; i = fix(j+1);
end;
jx = fix(jx + incx);
jy = fix(jy + incy);
end; j = fix(n+1);
end;
%
%        Form  A  when A is stored in the lower triangle.
%
elseif((incx==1) &&(incy==1) ) ;
for j = 1 : n;
if((x(j)~=zero) ||(y(j)~=zero) )
temp1 = alpha.*y(j);
temp2 = alpha.*x(j);
for i = j : n;
a(i,j) = a(i,j) + x(i).*temp1 + y(i).*temp2;
end; i = fix(n+1);
end;
end; j = fix(n+1);
else;
for j = 1 : n;
if((x(jx)~=zero) ||(y(jy)~=zero) )
temp1 = alpha.*y(jy);
temp2 = alpha.*x(jx);
ix = fix(jx);
iy = fix(jy);
for i = j : n;
a(i,j) = a(i,j) + x(ix).*temp1 + y(iy).*temp2;
ix = fix(ix + incx);
iy = fix(iy + incy);
end; i = fix(n+1);
end;
jx = fix(jx + incx);
jy = fix(jy + incy);
end; j = fix(n+1);
end;
%
%
%     end of SSYR2 .
%
a_shape=zeros(a_shape);a_shape(:)=a(1:numel(a_shape));a=a_shape;
x_shape=zeros(x_shape);x_shape(:)=x(1:numel(x_shape));x=x_shape;
y_shape=zeros(y_shape);y_shape(:)=y(1:numel(y_shape));y=y_shape;
end
%DECK SSYR2K