nag_sparse_sym_matvec (f11xec) Example Program Data
  9                   : n
 23                   : nnz
  4.    1     1
 -1.    2     1
  6.    2     2
  1.    3     2
  2.    3     3
  3.    4     4
  2.    5     1
  4.    5     5
  1.    6     3
  2.    6     4
  6.    6     6
 -4.    7     2
  1.    7     5
 -1.    7     6
  6.    7     7
 -1.    8     4
 -1.    8     6
  3.    8     8
  1.    9     1
  1.    9     5
 -1.    9     6
  1.    9     8
  4.    9     9       : (a, irow, icol)[i], i=0,...,nnz-1
  0.70  0.16  0.52 
  0.77  0.28  0.21
  0.93  0.20  0.90    : x[i], i=1,...,n-1 
 Nag_SparseSym_Check  : check