Givens Rotation

Product of a givens rotation matrix with a vector represents counter clockwise rotation on a given plane, by given degrees/radians.

Givens rotation matrix is defined by the following rules:

G(i, j, \theta) = M where:
  i > j
  M(k,k) = 1 for k!={i,j}
  M(k,k) = cos\theta for k={i,j}
  M(i,j) = -M(j,i) = -sin\theta
  M(x,y) = 0 else