COMPUTE RANKORDER

        [SIC\]COMPUTE OutVar RANKORDER InVar

    Compute  the order (sorting array) corresponding to the values in InVar,
    e.g.
      SIC> define real a[4] b[4]
      SIC> let a 10 15 12 9
      SIC> compute b rankorder a
      SIC> exa b
      B               is a real Array     of dimensions  4
         4.000000       1.000000       3.000000       2.000000

    InVar and OutVar are R*4 or R*8 variables, assumed to be 1-D  variables.
    This  can  be  used  e.g.  for statistical non-parametric tests like the
    Spearman test.