compute a = -.1.
compute b = 2.
compute c = 10.
COMPUTE x = rv.uniform(0,20) .
compute y = a*x*x +b*x+c.
IF (x>10) y = 20.
 comput y = y + rv.normal(0,1).
EXECUTE .
SORT CASES BY
  x (A) .

GRAPH
  /SCATTERPLOT(BIVAR)=x WITH y
  /MISSING=LISTWISE .



* NonLinear Regression.
MODEL PROGRAM B0=15  B1=1 B2=-.1 .
compute x0 = -b1/(2*b2).
do if (x <= x0) .
COMPUTE PRED_ = b0+b1*x+b2*x*x.
else.
compute pred_ = b0+b1*x0 + b2*x0*x0.
end if.
NLR y
  /OUTFILE='C:SPSSFNLR.TMP'
  /PRED PRED_
  /CRITERIA SSCONVERGENCE 1E-8 PCON 1E-8 .