program decimals(decimalsp, output);
(* decimals: determine the number of decimal places in a real number

  Dr. Thomas D. Schneider
  National Institutes of Health
  National Cancer Institute
  Center for Cancer Research Nanobiology Program
  Molecular Information Theory Group
  Frederick, Maryland  21702-1201
  toms@ncifcrf.gov
  permanent email: toms@alum.mit.edu (use only if first address fails)
  http://www.ccrnp.ncifcrf.gov/~toms/

 *)

label 1; (* end of program *)

const
(* begin module version *)
   version = 1.01; (* of decimals.p 2006 Sep 24
2006 Sep 24, 1.01: clean documentation
2006 Sep 24, 1.00: origin
*)
updateversion = 1.00; (* defines lowest acceptable current parameter file *)
(* end module version *)

(* begin module describe.decimals *)
(*
name
   decimals: determine the number of decimal places in a real number

synopsis
   decimals(decimalsp: in, output: out)

files

   decimalsp:  parameters to control the program.  The file must contain the
      following parameters, one per line:

      parameterversion: The version number of the program.  This allows the
         user to be warned if an old parameter file is used.

   output: messages to the user

description

   Determine the number of decimal places that a real number can hold.
   This is done by repeatedly dividing by 2 until the number becomes
   zero.

examples

documentation

see also

author

   Thomas Dana Schneider

bugs

technical notes

*)
(* end module describe.decimals *)

var
   decimalsp: text; (* file used by this program *)

(* begin module halt *)
procedure halt;
(* stop the program.  the procedure performs a goto to the end of the
   program.  you must have a label:
      label 1;
   declared, and also the end of the program must have this label:
      1: end.
   examples are in the module libraries.
   this is the only goto in the delila system. *)
begin
      writeln(output,' program halt.');
      goto 1
end;
(* end module halt version = 'delmod 6.16 84 mar 12 tds/gds'; *)

(* begin module decimals.themain *)
procedure themain(var decimalsp: text);
(* the main procedure of the program *)
var
   parameterversion: real; (* parameter version number *)
   x: real; (* the number *)
   p: real; (* previous x *)
begin
   writeln(output,'decimals ',version:4:2);
   reset(decimalsp);
   readln(decimalsp, parameterversion);
   if round(100*parameterversion) < round(100*updateversion) then begin
      writeln(output, 'You have an old parameter file!');
      halt
   end;

   x := 1.0;
   while x > 0 do begin
      writeln (output, x:1);
      x := x / 2.0;
   end;

end;
(* end module decimals.themain *)

begin
   themain(decimalsp);
1: end.