text: """ Skeletons and oriented boundary of a simplicial complex """
  from larlib import *
  
  
  """ Oriented boundary matrix visualization """
  np.set_printoptions(threshold='nan')
  csrSignedBoundaryMat = signedSimplicialBoundary (V,FV,EV)
  Z = csr2DenseMatrix(csrSignedBoundaryMat)
  print "\ncsrSignedBoundaryMat =\n", Z
  import matplotlib.pyplot
  from pylab import *
  matshow(Z)
  show()
  
  """  Computation of oriented boundary cells """
  boundaryCells_1 = signedBoundaryCells(V,FV,EV)
  print "\nboundaryCells_1 =\n", boundaryCells_1
  boundaryEV = [EV[-k] if k<0 else swap(EV[k]) for k in boundaryCells_1]
  bndry = (V,boundaryEV)
  VIEW(EXPLODE(1.5,1.5,1.5)(MKPOLS(bndry)))
  
  