/* conclk.sas                                        */
 /* Example 9.6 -- simple nonlinear regression        */
 /*  from Bates & Watts (1988, p41, Example BOD 1)    */
 /*                                                   */
  option ls = 80 ;           * easier to read output ;
  data a ;
    input x y ;
 cards ;
  1   8.3
  2  10.3
  3  19.0
  4  16.0
  5  15.6
  7  19.8
 ;
run ;
 /*                                                   */
 /*                     write out the data            */
  proc print data=a ;
    title 'Example 9.6 -- Simple nonlinear regression' ;
    title2 'Bates & Watts Example BOD 1' ;
run ;
 /*                                                   */
 /*                     nonlinear regression          */
  proc nlin data=a ;
    model y = th1*( 1 - exp(-th2*x) ) ;  * model gives mean function ;
    der.th1 = 1-exp(-th2*x) ;            * gradient vector ;
    der.th2 = th1*x*exp( -th2*x ) ;
    parameters th1 = 20  th2 = 0.4 ;     * initial values ;
 run ;