PROGRAM d9r3(input,output);
(* driver for routine ZBRAK *)
CONST
   n=100;
   nbmax=20;
   x1=1.0;
   x2=50.0;
TYPE
   glnbmax = ARRAY [1..nbmax] OF real;
VAR
   i,nb : integer;
   xb1,xb2 : glnbmax;

(*$I MODFILE.PAS *)
(*$I BESSJ0.PAS *)

FUNCTION fx(x: real): real;
BEGIN
   fx := bessj0(x)
END;

(*$I ZBRAK.PAS *)

BEGIN
   nb := nbmax;
   zbrak(x1,x2,n,xb1,xb2,nb);
   writeln;
   writeln('brackets for roots of bessj0:');
   writeln('lower':22,'upper':10,
         'f(lower)':16,'f(upper)':10);
   FOR i := 1 to nb DO BEGIN
      writeln('  root ',i:2,' ':4,xb1[i]:10:4,xb2[i]:10:4,
         ' ':4,fx(xb1[i]):10:4,fx(xb2[i]):10:4)
   END
END.