[M3devel] LONGINT problem?

[Rodney M. Bates]

I just checked in a fix to Convert.m3 for this into the release branch.
It now gives the expected results for LONGINT.  To rebuild, go into
the scripts subdirectory and type "./do-cm3-min.sh buildship".

This problem has already been fixed in the head in a different and more
efficient way.

On 07/14/2011 04:26 PM, Ken Durocher wrote:
 > 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;
 >
 > BEGIN
 > i := 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 Primitives
 > 1000: 325 Triples, 70 Primitives
 > 10000: 0858 Triples, 703 Primitives
 > 100000: 40701 Triples, 7024 Primitives
 > 1000000: 808950 Triples, 70229 Primitives
 >
 > However, if I just use INTEGER on a 64 bit machine, I get the proper output:
 >
 > 100: 17 Triples, 7 Primitives
 > 1000: 325 Triples, 70 Primitives
 > 10000: 4858 Triples, 703 Primitives
 > 100000: 64741 Triples, 7026 Primitives
 > 1000000: 808950 Triples, 70229 Primitives
 >
 > Note how 10000 and 100000 are different. The code is literally exactly the same, only with LONGINT replaced by INTEGER.