rotate

rotate — rotation of a set of points

Calling sequence

xy1=rotate(xy,[theta,orig])

Parameters

`xy`	: matrice of size (2,.).
`xy1`	: matrice of size (2,.).
`theta`	: real, angle en radian; default value is 0.
`orig`	: center of the rotation; default value is [0;0].

Description

rotate performs a rotation with angle theta:

xy1(:,i) = M(theta) *xy (:,i) + orig

where M stands for the corresponding rotation matrix.

Examples



xsetech([0,0,1,1],[-1,-1,1,1])
xy=[(0:0.1:10);sin(0:0.1:10)]/10;
for i=2*%pi*(0:10)/10,
  [xy1]=rotate(xy,i);
  xpoly(xy1(1,:),xy1(2,:),"lines")
end