Subj : Re: Dartmouth BASIC to C
To   : comp.programming
From : jimmaureenrogers@worldnet.att.net
Date : Mon Aug 08 2005 05:06 pm


Jon Harrop wrote:
> John Smith wrote:
>
> > Having nothing better to do on a Saturday morning, I was looking at
> > Kemeny & Kurtz's 1964 manual for BASIC:
> >
> > http://www.bitsavers.org/pdf/dartmouth/BASIC_Oct64.pdf
> >
> > Below is a C port of the first example program given in the manual. Can
> > it be improved while preserving, as much as possible, the structure of
> > the original BASIC program?
>
> I've no idea, but here's an OCaml port, just for fun:

<snip>

And here is an Ada port, just for fun:

-----------------------------------------------------------------------
--  An Ada port of the 1st program given in Kemeny & Kurtz's
--  manual for 1964 Dartmouth BASIC. It solves a system of
--  linear equations with three different right sides.
--  (A1*X1) + (A2*X2) = B1
--  (A3*X1) + (A4*X2) = B2
-----------------------------------------------------------------------

with Ada.Text_Io; use Ada.Text_Io;

procedure Linear is
   type Pairs is array(1..2) of Float;
   type Pair_List is array(1..3) of Pairs;
   Data : constant Pair_List := ((-7.0, 5.0), (1.0, 3.0), (4.0, -7.0));
   A1, A2, A3, A4 : Float;
   D : Float;
   X1, X2, B1, B2 : Float;
begin
   A1 := 1.0;
   A2 := 2.0;
   A3 := 4.0;
   A4 := 2.0;
   D := A1 * A4 - A3 * A2;
   if D = 0.0 then
      Put_Line("NO UNIQUE SOLUTION");
   else
      for I in Data'range loop
         B1 := Data(I)(1);
         B2 := Data(I)(2);
         X1 := (B1 * A4 - B2 * A2) / D;
         X2 := (A1 * B2 - A3 * B1) / D;
         Put_Line(Float'Image(X1) & " " & Float'Image(X2));
      end loop;
   end if;
end Linear;

I notice that the formulas in the comment differ from the formulae in
the code (comments have a "+" while the code has a "-").

Jim Rogers

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