function A = Gives(A,i,j)
% Apply Givens Rotation for a symmetric matrix A
%               H. Hasegawa; July 2, 2006
s=size(A); R=eye(s(1)); 
th = atan(2*A(i,j)/(A(i,i)-A(j,j)))/2;
R(i,i) = cos(th); R(i,j) = -sin(th); R(j,i) = sin(th); R(j,j)=cos(th);
A = R'*A*R;