 Usage:  surv = hazsurv(data,z)  
 
 Input:

  data                   n x (p+4) matrix, 
                         column 1: the sorted observed survival time t, 
                         column 2: the cosorted censoring indicator delta, 
                         column 3: labels l, 
                         column 4: number of ties at time t[i], cosorted, 
                         columns 5 to p+4: the cosorted covariate matrix z. 
                         
  z                      p x 1 matrix, the covariate values for which the 
                         conditional survival curve is estimated. 
                         
 Output:

  surv                   n x 2 matrix, the first column is the sorted 
                         t, followed by the estimated survival function 
                         at the points of t, conditional on z. 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
