Definition: inverse mapping
t = (z-z1)/(z2-z1)
theta = (1-t)*theta1 + t*theta2
x'=x*cos(theta)+y*sin(theta)
y'=-x*sin(theta)+y*cos(theta)

Call: hfTwistZ(xt,z1,z2,theta1,theta2);

Parameters:

xt - point coordinates array to be changed

z1, z2 - end points of z-interval

theta1, theta2 - rotation angles in radians for end points

Test file: twist.hf

Definition: inverse mapping
t = (y-y1)/(y2-y1)
theta = (1-t)*theta1 + t*theta2
z'=z*cos(theta)+x*sin(theta)
x'=-z*sin(theta)+x*cos(theta)

Call: hfTwistY(xt,z1,z2,theta1,theta2);

Parameters:

xt - point coordinates array to be changed

z1, z2 - end points of z-interval

theta1, theta2 - rotation angles in radians for end points

Test file: twist.hf

Definition: inverse mapping
t = (x-x1)/(x2-x1)
theta = (1-t)*theta1 + t*theta2
y'=y*cos(theta)+z*sin(theta)
z'=-y*sin(theta)+z*cos(theta)

Call: hfTwistX(xt,z1,z2,theta1,theta2);

Parameters:

xt - point coordinates array to be changed

z1, z2 - end points of z-interval

theta1, theta2 - rotation angles in radians for end points

Test file: twist.hf