sparse_test():
  Python version: 3.6.9
  sparse is a scipy library of functions for dealing with
  sparse matrices.

sparse_test01()
  Define a tiny sparse matrix.

  COO storage:

  (0, 0)	11.0
  (0, 1)	12.0
  (0, 4)	15.0
  (1, 1)	22.0
  (1, 2)	23.0
  (2, 0)	31.0
  (2, 2)	33.0
  (2, 3)	34.0
  (2, 4)	35.0

  Printed as an array:

[[11. 12.  0.  0. 15.]
 [ 0. 22. 23.  0.  0.]
 [31.  0. 33. 34. 35.]]

sparse_test02():
  Create a sparse second difference matrix.
  Solve an associated linear system.

  Matrix in coo format:

  (1, 0)	-1.0
  (2, 1)	-1.0
  (3, 2)	-1.0
  (4, 3)	-1.0
  (0, 0)	2.0
  (1, 1)	2.0
  (2, 2)	2.0
  (3, 3)	2.0
  (4, 4)	2.0
  (0, 1)	-1.0
  (1, 2)	-1.0
  (2, 3)	-1.0
  (3, 4)	-1.0

  Matrix as an array:

[[ 2. -1.  0.  0.  0.]
 [-1.  2. -1.  0.  0.]
 [ 0. -1.  2. -1.  0.]
 [ 0.  0. -1.  2. -1.]
 [ 0.  0.  0. -1.  2.]]

  Solution to linear system:

[1. 2. 3. 4. 5.]

sparse_test():
  Normal end of execution.