load pdb1.xyz;
x = pdb1(:,2);
y = pdb1(:,3);
z = pdb1(:,4);


res(size(x)) = 0 ;
for i=1:size(x) - 3
	j = i ;
	a = [x(j+1)-x(j), y(j+1)-y(j), z(j+1)-z(j)];
	j = i+1 ;
	b = [x(j+1)-x(j), y(j+1)-y(j), z(j+1)-z(j)];
	j = i+2 ;
	c = [x(j+1)-x(j), y(j+1)-y(j), z(j+1)-z(j)];

	alpha = cross(a,b);
	beta = cross(b,c);
	res1(i) = dot(alpha,beta);
        alpha = alpha / norm(alpha);
        beta = beta / norm(beta) ;
        res2(i) = dot(alpha,beta);
end