diff options
Diffstat (limited to 'generic')
| -rwxr-xr-x | generic/tclStrToD.c | 32 | ||||
| -rw-r--r-- | generic/tclUtil.c | 54 |
2 files changed, 77 insertions, 9 deletions
diff --git a/generic/tclStrToD.c b/generic/tclStrToD.c index 51a1a58..53ffedd 100755 --- a/generic/tclStrToD.c +++ b/generic/tclStrToD.c @@ -12,7 +12,7 @@ * See the file "license.terms" for information on usage and redistribution of * this file, and for a DISCLAIMER OF ALL WARRANTIES. * - * RCS: @(#) $Id: tclStrToD.c,v 1.52 2010/12/07 16:27:39 dkf Exp $ + * RCS: @(#) $Id: tclStrToD.c,v 1.53 2011/01/15 18:10:19 kennykb Exp $ */ #include "tclInt.h" @@ -3086,6 +3086,11 @@ StrictInt64Conversion( if (i == ilim) { if (2*b > S || (2*b == S && (digit & 1) != 0)) { s = BumpUp(s, retval, &k); + } else { + while (*--s == '0') { + /* do nothing */ + } + ++s; } break; } @@ -3330,6 +3335,11 @@ ShorteningBignumConversionPowD( *s++ = '9'; s = BumpUp(s, retval, &k); break; + } else if (mp_iszero(&b)) { + while (*--s == '0') { + /* do nothing */ + } + ++s; } } @@ -3494,6 +3504,10 @@ StrictBignumConversionPowD( if (ShouldBankerRoundUpPowD(&b, sd, digit&1)) { s = BumpUp(s, retval, &k); } + while (*--s == '0') { + /* do nothing */ + } + ++s; break; } @@ -3766,7 +3780,7 @@ ShorteningBignumConversion( --s5; /* - * TODO: It might possibly be a win to fall back to int64 + * IDEA: It might possibly be a win to fall back to int64 * arithmetic here if S < 2**64/10. But it's a win only for * a fairly narrow range of magnitudes so perhaps not worth * bothering. We already know that we shorten the @@ -3966,6 +3980,10 @@ StrictBignumConversion( } } } + while (*--s == '0') { + /* do nothing */ + } + ++s; /* * Endgame - store the location of the decimal point and the end of the @@ -4023,9 +4041,10 @@ StrictBignumConversion( * choosing the one that is closest to the given number (and * resolving ties with 'round to even'). It is allowed to return * fewer than 'ndigits' if the number converts exactly; if the - * TCL_DD_E_FORMAT|TCL_DD_SHORTEN_FLAG is supplied instead, it is - * also allowed to return fewer digits if the shorter string will - * still reconvert to the given input number. + * TCL_DD_E_FORMAT|TCL_DD_SHORTEN_FLAG is supplied instead, it + * also returns fewer digits if the shorter string will still + * reconvert without loss to the given input number. In any case, + * strings of trailing zeroes are suppressed. * TCL_DD_F_FORMAT - This value is used to prepare numbers for %f format * conversion. It requests that conversion proceed until * 'ndigits' digits after the decimal point have been converted. @@ -4035,7 +4054,8 @@ StrictBignumConversion( * number that converts exactly, and changing the argument to * TCL_DD_F_FORMAT|TCL_DD_SHORTEN_FLAG will allow the routine * also to return fewer digits if the shorter string will still - * reconvert without loss to the given input number. + * reconvert without loss to the given input number. Strings of + * trailing zeroes are suppressed. * * To any of these flags may be OR'ed TCL_DD_NO_QUICK; this flag requires * all calculations to be done in exact arithmetic. Normally, E and F diff --git a/generic/tclUtil.c b/generic/tclUtil.c index 984ba0a..f746aed 100644 --- a/generic/tclUtil.c +++ b/generic/tclUtil.c @@ -11,7 +11,7 @@ * See the file "license.terms" for information on usage and redistribution of * this file, and for a DISCLAIMER OF ALL WARRANTIES. * - * RCS: @(#) $Id: tclUtil.c,v 1.123 2010/12/03 22:30:56 hobbs Exp $ + * RCS: @(#) $Id: tclUtil.c,v 1.124 2011/01/15 18:10:19 kennykb Exp $ */ #include "tclInt.h" @@ -2273,7 +2273,47 @@ Tcl_PrintDouble( digits = TclDoubleDigits(value, -1, TCL_DD_SHORTEST, &exponent, &signum, &end); } else { - digits = TclDoubleDigits(value, *precisionPtr, TCL_DD_E_FORMAT, + /* + * There are at least two possible interpretations for tcl_precision. + * + * The first is, "choose the decimal representation having + * $tcl_precision digits of significance that is nearest to the + * given number, breaking ties by rounding to even, and then + * trimming trailing zeros." This gives the greatest possible + * precision in the decimal string, but offers the anomaly that + * [expr 0.1] will be "0.10000000000000001". + * + * The second is "choose the decimal representation having at + * most $tcl_precision digits of significance that is nearest + * to the given number. If no such representation converts + * exactly to the given number, choose the one that is closest, + * breaking ties by rounding to even. If more than one such + * representation converts exactly to the given number, choose + * the shortest, breaking ties in favour of the nearest, breaking + * remaining ties in favour of the one ending in an even digit." + * + * Tcl 8.4 implements the first of these, which gives rise to + * anomalies in formatting: + * + * % expr 0.1 + * 0.10000000000000001 + * % expr 0.01 + * 0.01 + * % expr 1e-7 + * 9.9999999999999995e-08 + * + * For human readability, it appears better to choose the second rule, + * and let [expr 0.1] return 0.1. But for 8.4 compatibility, we + * prefer the first (the recommended zero value for tcl_precision + * avoids the problem entirely). + * + * Uncomment TCL_DD_SHORTEN_FLAG in the next call to prefer the + * method that allows floating point values to be shortened if + * it can be done without loss of precision. + */ + + digits = TclDoubleDigits(value, *precisionPtr, + TCL_DD_E_FORMAT /* | TCL_DD_SHORTEN_FLAG */, &exponent, &signum, &end); } if (signum) { @@ -2294,7 +2334,15 @@ Tcl_PrintDouble( c = *++p; } } - sprintf(dst, "e%+d", exponent); + /* + * Tcl 8.4 appears to format with at least a two-digit exponent; + * preserve that behaviour when tcl_precision != 0 + */ + if (*precisionPtr == 0) { + sprintf(dst, "e%+d", exponent); + } else { + sprintf(dst, "e%+03d", exponent); + } } else { /* * F format for others. |