source: MML/trunk/mml/at/mksrollmat.m @ 4

function R = mksrollmat(PSI);
%MKSROLLMAT - Rotation matrix around s-axis
% M = MKSROLLMAT(PSI) makes a 6-by-6 coordinate transformation matrix
% that transforms 6-by-1 phase space coordinate vector of the PARTICLE
% to a new coord system.  PSI is in radians.
%
% The new system is rotated around the s-axis 
% with respect to the old system by an angle PSI
% POSITIVE PSI corresponds to a CORKSCREW (right) 
% rotation of the ELEMENT.
% 
% The matrix only transforms the transverse (X,PX,Y,PY) coordinates
% 
% In AT, this matrix is used for R1,R2 field of the element 
% data structure in a lattice. Some pass-methods use them
% along with T1 and T2 to includ ELEMENT misalignment
% If a straight ELEMENT (such a quadrupole) is rotated
% by a positive angle PSI (ANTICLOCKWISE)  then 
% R1 = mksrollmat(PSI)
% R2 = mksrollmat(-PSI)
% clockwise (corkscrew aligned with the reference orbit direction)

C = cos(PSI);
S = sin(PSI);
R = diag([ C C C C 1  1 ]);
R(1,3) = S;
R(2,4) = S;
R(3,1) = -S;
R(4,2) = -S;