 Usage:  {betahat, betak, ck} = hazbeta(data, {maxit})  
 
 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. 
                         
  maxit                  scalar, maximum number of iteration for the 
                         Newton-Raphson procedure, default = 40. 
                         
 Output:

  betahat                p x 1 vector, estimate of the regression 
                         parameter beta 
                         
  betak                  maxit x p matrix, parameter values through the 
                         Newton-Raphson procedure 
                         
  ck                     maxit x 1 vector, convergence criteria values 
                         through the Newton-Raphson procedure 
                         
--------------------------------------------------------------
(C) MD*TECH Method and Data Technologies, 17.8.2000
