 the origin.  This
 may be useful if the original data points were all from a hypershpere --
 for example they were normalized via imNormalize.  Set the optional
 hypershpere flag to 1 to generate points only on the hypersphere.

 USAGE
  Xr = pcaRandVec( U, mu, vars, k, n, [hypershpere], [show] )

 INPUTS
  U           - returned by pca.m
  mu          - returned by pca.m
  vars        - returned by pca.m
  k           - number of principal coordinates to use
  n           - number of points t