 Usage:  {cil, kme, ciu} = hazkpm(data{,alpha})  
 
 Input:

  data                   n x (p+4) matrix, the first column is the sorted 
                         survival time t, followed by the sorted delta, 
                         inidcating if censoring has occured, labels l, a 
                         column containing the number of ties, and lastly, 
                         the sorted covariate matrix z. 
                         
  alpha                  scalar, the confidence level, optional, 
                         default = 0.05 
                         
 Output:

  cil                    n x 2 matrix, the first column is the sorted 
                         t, followed by the Greenwood lower confidence 
                         bound for the survival function at the points of t. 
                         
  kme                    n x 2 matrix, the first column is the sorted 
                         t, followed by the Kaplan-Meier estimates of the 
                         survival function at the points of t. 
                         
  ciu                    n x 2 matrix, the first column is the sorted 
                         t, followed by the Greenwood upper confidence 
                         bound for the survival function at the points of t. 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
