 Usage:  {ll,ll1,ll2} = hazregll(data, beta)  
 
 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. 
                         
  beta                   p x 1 vector, the parameter, coefficients of the 
                         covariate. 
                         
 Output:

  ll                     scalar, the log-likelihood function at 
                         parameter value beta 
                         
  ll1                    p x 1 vector, the first derivatives at parameter 
                         value beta of the log-likelihood function 
                         
  ll2                    p x p matrix, negative Hessian matrix at parameter 
                         value beta of the log-likelihood function 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
