 Usage:  inrisk = hazrisk(data,i)  
 
 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. 
                         This data matrix may be obtained through hazdat.xpl. 
                         
  i                      an integer between 1 and n. 
                         
 Output:

  inrisk                 n x 1 vector, the jth entry is 1 if the jth 
                         observation is at risk at time i, 0 otherwise. 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
