home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Cream of the Crop 1
/
Cream of the Crop 1.iso
/
PROGRAM
/
NRPAS13.ARJ
/
ZBRAC.PAS
< prev
next >
Wrap
Pascal/Delphi Source File
|
1991-04-29
|
759b
|
31 lines
PROCEDURE zbrac(VAR x1,x2: real; VAR succes: boolean);
(* Programs using routine ZBRAC must externally define a
function fx(x:real):real which is to be bracketed. *)
LABEL 99;
CONST
factor=1.6;
ntry=50;
VAR
j: integer;
f2,f1: real;
BEGIN
IF (x1 = x2) THEN BEGIN
writeln('pause in routine ZBRAC');
writeln('you have to guess an initial range'); readln
END;
f1 := fx(x1);
f2 := fx(x2);
succes := true;
FOR j := 1 TO ntry DO BEGIN
IF (f1*f2 < 0.0) THEN GOTO 99;
IF (abs(f1) < abs(f2)) THEN BEGIN
x1 := x1+factor*(x1-x2);
f1 := fx(x1)
END ELSE BEGIN
x2 := x2+factor*(x2-x1);
f2 := fx(x2)
END
END;
succes := false;
99: END;