[M3devel] LONGINT problem?

Fri Jul 15 03:30:49 CEST 2011

Hi all:
the problem as I see is that your program isn't typed for any platform in specific just to give you the best answer, then I would stick to the original and track down the source of the problem (this is very point of type checking, and e.g extended static checking if I may say so, the need to verify your statements, the other approach is too cumbersome, i.e make it believe it works when it doesn't). IMHO this a symptom of UNSAFE type checking problem, rather of programming or programmer error.
I hope to be clarified about this, as far as I know LONGINT isn't INTEGER but a bigger or equal type (a bigger INTEGER) which translates better to be a super type, since it isn't I wonder why is that needed a different type checker for that (we can transform INTEGER to be the true super type and LONGINT to be a subtype), can't we make the same checking and just range check everything else (so it doesn't bother to rewrite every platform code, a bad symptom certainly, yet I approve the change in the language SPEC but not its type checking).
Thanks in advance

--- El jue, 14/7/11, Coleburn, Randy <rcolebur at SCIRES.COM> escribió:

De: Coleburn, Randy <rcolebur at SCIRES.COM>
Asunto: Re: [M3devel] LONGINT problem?
Para: "m3devel" <m3devel at elegosoft.com>, "Ken Durocher" <kcdurocher at gmail.com>
Fecha: jueves, 14 de julio, 2011 18:15

Ken:  On what platform (OS and CPU) are you building and running your Modula-3 program?  Support for LONGINT is a relatively new addition to CM3, so it is possible that something is broken.  Perhaps your program can help us track it down.    I haven’t checked thru your program yet, but the fact that it gives the right answer using INTEGER, but not when using LONGINT, seems to point to the LONGINT implementation as a potential problem source we should investigate.  Regards,Randy Coleburn  From: Ken Durocher [mailto:kcdurocher at gmail.com] 
Sent: Thursday, July 14, 2011 7:00 PM
To: Jay K
Cc: m3devel
Subject: Re: [M3devel] LONGINT problem?  Sorry, to clarify, the LONGINT code does NOT give the correct output, but the INTEGER code DOES.  I did not write this C code, but it's output is the same as all the other examples (there is a Java example too, if you want that):  #include <stdio.h>#include <stdlib.h>#include <stdint.h> /* should be 64-bit integers if going over 1 billion */typedef unsigned long xint;#define FMT "%lu" xint total, prim, max_peri;xint U[][9] =  {{ 1, -2, 2,  2, -1, 2,  2, -2, 3},                        { 1,  2, 2,  2,  1, 2,  2,  2, 3},                        {-1,  2, 2, -2,  1, 2, -2,  2, 3}}; void new_tri(xint in[]){            int i;            xint t[3], p = in[0] + in[1] + in[2];             if (p > max_peri) return;             prim ++;             /* for every primitive triangle, its multiples would be
 right-angled too;            * count them up to the max perimeter */            total += max_peri / p;             /* recursively produce next tier by multiplying the matrices */            for (i = 0; i < 3; i++) {                        t[0] = U[i][0] * in[0] + U[i][1] * in[1] + U[i][2] * in[2];                        t[1] = U[i][3] * in[0] + U[i][4] * in[1] + U[i][5] * in[2];                        t[2] = U[i][6] * in[0] + U[i][7] * in[1] + U[i][8] * in[2];                        new_tri(t);            }} int main(){            xint seed[3] = {3, 4, 5};             for (max_peri = 10; max_peri <= 100000000; max_peri *= 10) {                        total = prim = 0;                       
 new_tri(seed);                         printf(  "Up to "FMT": "FMT" triples, "FMT" primitives.\n",                                    max_peri, total, prim);            }            return 0;}  The output from that code is:  Up to 10: 0 triples, 0 primitives.Up to 100: 17 triples, 7 primitives.Up to 1000: 325 triples, 70 primitives.Up to 10000: 4858 triples, 703 primitives.Up to 100000: 64741 triples, 7026 primitives.Up to 1000000: 808950 triples, 70229 primitives.Up to 10000000: 9706567 triples, 702309 primitives.Up to 100000000: 113236940 triples, 7023027 primitives.  Note this output corresponds with the INTEGER output.  On Thu, Jul 14, 2011 at 5:17 PM, Jay K <jay.krell at cornell.edu> wrote:Can you isolate if the problem is the formating/printing, or if it is in the computation?
i.e.:

Use "unsafe" and print out a little hex dump of the integer/longint variables?

As well, what does LONGINT on a 64bit machine do? Eh..well, it might work, it might not.
Doesn't really matter. Let's focus on non-working 32bit machine with LONGINT.

Also, please confirm which is the right, i.e. by writing it in C.
Also, maybe just try to format as unsigned/hex using the safe interfaces?
Also, this will be good to add to our automated tests. Assuming it doesn't run too slowly.
Assuming it reproduces for anyone else (sorry, a bit rude of me).

Later, thank you,
 - Jay

Date: Thu, 14 Jul 2011 16:26:05 -0500
From: kcdurocher at gmail.com
To: m3devel at elegosoft.com
Subject: [M3devel] LONGINT problem?

I was writing a program to calculate "Pythagorean triples" recursively, and ran into a problem.  Here's the program:  MODULE PyTriples EXPORTS Main;  IMPORT IO, Fmt;  VAR tcnt, pcnt, max, i: LONGINT;  PROCEDURE NewTriangle(a, b, c: LONGINT; VAR tcount, pcount: LONGINT) =  VAR perim := a + b + c;        BEGIN    IF perim <= max THEN      pcount := pcount + 1L;      tcount := tcount + max DIV perim;      NewTriangle(a-2L*b+2L*c, 2L*a-b+2L*c, 2L*a-2L*b+3L*c, tcount, pcount);      NewTriangle(a+2L*b+2L*c, 2L*a+b+2L*c, 2L*a+2L*b+3L*c, tcount, pcount);      NewTriangle(2L*b+2L*c-a, b+2L*c-2L*a, 2L*b+3L*c-2L*a, tcount, pcount);    END;  END NewTriangle;  BEGINi := 100L;  REPEAT  max := i;  tcnt := 0L;  pcnt := 0L;  NewTriangle(3L, 4L, 5L, tcnt, pcnt);  IO.Put(Fmt.LongInt(i) & ": " & Fmt.LongInt(tcnt) & " Triples, " &    Fmt.LongInt(pcnt) & " Primitives\n");  i := i * 10L;UNTIL i = 10000000L;  END PyTriples.  This
 outputs:  100: 17 Triples, 7 Primitives1000: 325 Triples, 70 Primitives10000: 0858 Triples, 703 Primitives100000: 40701 Triples, 7024 Primitives1000000: 808950 Triples, 70229 Primitives  However, if I just use INTEGER on a 64 bit machine, I get the proper output:  100: 17 Triples, 7 Primitives1000: 325 Triples, 70 Primitives10000: 4858 Triples, 703 Primitives100000: 64741 Triples, 7026 Primitives1000000: 808950 Triples, 70229 Primitives  Note how 10000 and 100000 are different. The code is literally exactly the same, only with LONGINT replaced by INTEGER.    
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