vishapoberon/compiler
1
0
Fork 0
mirror of https://github.com/vishapoberon/compiler.git synced 2026-10-10 07:27:23 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

fixing Out.Real and Out.LongReal: the exponent missed the rounding carry

Browse source 
the exponent digits were written before the mantissa was rounded, so
a carry into the next power of ten was lost: 0.99999999999999989
came out as 1.0D-001, and Math.sqrt(1.0) as 1.00000E-01.
This commit is contained in:
Norayr Chilingarian 2026-10-06 20:14:31 +04:00
parent 9701249ad2
commit d6d99b4fbe
1 changed files with 7 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

13
src/runtime/Out.Mod
View file

@ -183,11 +183,6 @@ BEGIN
IF e >= 0 THEN x := x / Ten(e) ELSE x := Ten(-e) * x END ; IF e >= 0 THEN x := x / Ten(e) ELSE x := Ten(-e) * x END ;
IF x >= 10.0D0 THEN x := 0.1D0 * x; INC(e) END; IF x >= 10.0D0 THEN x := 0.1D0 * x; INC(e) END;
(* Generate the exponent digits *)
en := e < 0; IF en THEN e := - e END;
WHILE el > 0 DO digit(e, s, i); e := e DIV 10; DEC(el) END;
DEC(i); IF en THEN s[i] := "-" ELSE s[i] := "+" END;
(* Scale x to enough significant digits to reliably test for trailing (* Scale x to enough significant digits to reliably test for trailing
zeroes or to the amount of space available, if greater. *) zeroes or to the amount of space available, if greater. *)
x0 := Ten(d-1); x0 := Ten(d-1);
@ -196,7 +191,13 @@ BEGIN
introduces a least significant bit difference introduces a least significant bit difference
between 32 bit and 64 bit builds. *) between 32 bit and 64 bit builds. *)
IF x >= 10.0D0 * x0 THEN x := 0.1D0 * x; INC(e) END; IF x >= 10.0D0 * x0 THEN x := 0.1D0 * x; INC(e) END;
m := Entier64(x) m := Entier64(x);
(* Generate the exponent digits, after the rounding above, which can carry into it
(0.99999999999999989 was written as 1.0D-001) *)
en := e < 0; IF en THEN e := - e END;
WHILE el > 0 DO digit(e, s, i); e := e DIV 10; DEC(el) END;
DEC(i); IF en THEN s[i] := "-" ELSE s[i] := "+" END
END; END;
DEC(i); IF long THEN s[i] := "D" ELSE s[i] := "E" END; DEC(i); IF long THEN s[i] := "D" ELSE s[i] := "E" END;