On Wed, 2017-08-23 at 06:01 -0700, Rich Shepard wrote: > On Tue, 22 Aug 2017, Alan wrote: > > > Sometimes a rewrite is a useful and needed thing. > > Thanks, Alan, for allowing us to share our obscure bug experiences > on this > thread. :-) > > In grad school in 1972 I wrote an ecosystem ecological energy flow > model > in FORTRAN IV to run on the U. of Illinois' IBM S/360. It used more > than a > whole box of 80-column Hollerith cards for input. When it ran it > produed > incorrect results, but only the same 2 or 3 wrong answers each time. > So I > printed the source code listing on the wide green-bar paper that all > the > line printers used. The output was about 1 inch thick. > > I carefully examined each line of code multiple times without > seeing the > error. Finally, I took the printed listing to the computer center's > help > desk. They examined it without finding the problem. > > One day, strictly by chance while looking at a new printed copy > (likely > done on a printer with a newer ribbon) I saw the error jump up and > bite me > on the nose. > > Instead of a loop index written as FOR I = 1 TO N I had mistyped > it as FOR > 1 = 1 TO N. Distinguishing 1 from the uppercase I was difficult and, > because > all of us expected to see I and not 1 in that position we all > overlooked it. > > Haven't forgotten this after all these years. >
That is one of the first lessons you learn if you learned to type on a Royal manual typewriter. Looking for 0 and O is another. I remember the days of Fortran and punch cards. I still remember how to make Lace Cards. _______________________________________________ PLUG mailing list PLUG@lists.pdxlinux.org http://lists.pdxlinux.org/mailman/listinfo/plug