 Usage:  {val, df, pval} = haztest(data, index)  
 
 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. 
                         
  index                  p x 1 vector, with ith element = 0 when beta_i = 0 
                         is in the null hypothesis, and 1, otherwise. 
                         
 Output:

  val                    3 x 1 vector, values of the test statistics. 
                         
  df                     scalar, degree of freedom. 
                         
  pval                   3 x 1 vector, P-values of the tests. 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
