[Gm2] Another problem with MAX(LONGREAL);

[Michael Riedl]

Gaius,

maybe related to the last message - but may be independend from that

Have a look on the following short example

MODULE MaxReal2;

IMPORT STextIO,SLongIO,SWholeIO;

VAR   x : LONGREAL;
      i : CARDINAL;

BEGIN
      x:=MAX(LONGREAL);

      STextIO.WriteString("MAX(LONGREAL) = ");
      SLongIO.WriteEng(x,8,16); (* crashes *)
      STextIO.WriteLn;

      REPEAT (* does not terminate *)
        INC(i);
        x:=0.1*x;
        IF ((i MOD 100) = 0) THEN
          STextIO.WriteString("i = ");
          SWholeIO.WriteCard(i,8);
          STextIO.WriteLn;
        END;
      UNTIL (x < 1000.0);

      STextIO.WriteString("Number of devision by 10 = ");
      SWholeIO.WriteCard(i,8);
      STextIO.WriteLn;

END MaxReal2.

The output of MAX(LONGREAL) crashed - maybe something is wrong on the
representation ? At test for NaN (IF (x # x) ) did not yield a result
maybe it's INF ? That would explain the behaviour. 

As I saw that LongReal is 12 Byte long my own test routines do not work
and I don't have a clue about the representation of that kind of
numbers. If it where INF all exponet bit should be set and all mantissa
bits should be not set accoring to IEEE 754 - but I'm not sure here.

Attached my test routines which where designed to 4 BYTE REAL and 8
BYTE LONGREAL (which I assumed in most of my numerical code). If there
something of interrest in that module - feel free to use that (but please 
cross-check the code ;-) ).

Gruß / Regards

Michael

TestReal.tar
Description: Unix tar archive