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bblaplacian  Create a discrete Laplace-operator
  BB=bblaplacian(DIM1) creates a black-box operator which computes the
  discrete Laplace-operator on a hypercube with dimension given in DIM1.
  The resulting hypercube has the same dimension as the input, and is computed
  adduming all values outside the hypercube is zero.

  The finite-difference stencil is [1,-2,1] for 1D-problems. This is applied
  to each dimension of the hypercube and summed.

  Example: Poisson's equation with Dirichlet boundary condition zero of a
  rectangular domain with 100-by-200 internal nodes, amounts to solving
  BB*X=F(:), where F contains the function values on the internal nodes, and

  See also , , bbconvn.