(*$B- *)
PROGRAM integral;
VAR a,b,eps, int :real; i, z,fall:integer;
    tf:text; stri:string[20];

FUNCTION f(x:real):real;
BEGIN
   CASE fall OF
   (*$I F.PAS*)
   END;
   z := z + 1;
END;

(*$I trapez Algorithmus 7.1  *)
(*$I simpson Algorithmus 7.2 *)
(*$I romberg Algorithmus 7.3 *)

FUNCTION ada(a,b,eps:real):real;
VAR fa,fb,fm, is :real; v:integer;
(*$I adapt Algorithmus 7.4 *)
BEGIN
  fa:=f(a); fm:=f((a+b)/2); fb:=f(b);
  is := (b-a)/6*(fa+4*fm+fb) ;
  v:=1; IF is<0 THEN v:=-1;
  is := v*(abs(is)+b-a)/2*eps/1e-11;
  writeln(tf,'a':5,'b-a':15,'i1':16);
  ada:= adapt(a,b,fa,fm,fb,is);
END;

PROCEDURE menue;
VAR f:text; stri: string[100];
BEGIN
   assign(f,'F.PAS'); reset(f);
   WHILE NOT eof(f) DO
   BEGIN
      readln(f,stri); writeln(stri)
   END;
END;

BEGIN
  writeln('Wohin mit dem Output ?');
  read(stri); assign(tf,stri); rewrite(tf);
  menue;
  writeln('Fall');read(fall);
  writeln('a,b und eps eingeben'); read(a,b,eps);
  REPEAT
     writeln; writeln('Welche Integrationsmethode ?');
     writeln('0: fertig ');
     writeln('1: Trapezregel 2: Simpson ');
     writeln('3: Romberg     4: Adaptive Quadratur ');
     read(i); z := 0;
     IF i IN [1,2,3,4] THEN
     BEGIN
       CASE i OF
         1:  int:= trapez(a,b,eps);
         2:  int:= simpson(a,b,eps);
         3:  int := romberg(a,b,eps);
         4:  int := ada(a,b,eps);
       END;
       write(tf,'Integral = ',int);
       writeln(tf,'  Anzahl Fkt.Aufr. ',z);
     END;
  UNTIL i=0;
  close(tf)
END.