%STRAINTR Stress rotation.
% [STRAINSTATE]=STRAINTR([EPSX,EPSY,GAMXY],THETA) will take the given strain
% state and rotate it through the given radian angle THETA.
% EPSX: Normal stress in the X direction.
% EPSY: Normal stress in the Y direction.
% GAMXY: Shear on the X-Y plane.
% Together these three are gathered as the STRAINSTATE.
% THETA: The radian angle of rotation. Positive C.C.W. from right.
% EXP: Normal stress in the X prime direction.
% EYP: Normal stress in the Y prime direction.
% GXPYP: Shear stress in the X prime - Y prime plane.
% Together these three are gathered as a STRAINSTATE.
% See also MOHRS2, PPSTRAIN, PRISTRAIN, ROSETTE, STRAIN2STRESS.
% Details are to be found in Mastering Mechanics I, Douglas W. Hull,
% Prentice Hall, 1998
% Douglas W. Hull, 1998
% Copyright (c) 1998-99 by Prentice Hall
% Version 1.00
exp=(ex+ey)/2 + (ex-ey)/2*cos(2*theta) + gxy/2*sin(2*theta);
eyp=(ex+ey)/2 + (ex-ey)/2*cos(2*(theta+DR(90))) + gxy/2*sin(2*(theta+DR(90)));