I don't quite understand. Can you give us a few examples, how they are
handled by PHP today and how they would be handled by your code.
I'll start off:
0.9+0.1
0.9+0.0000001
8/10.0 + 0.2
I'm sure you know of juicier examples :)
Andi
At 02:33 PM 6/26/2002 +0100, George Whiffen wrote:
>Oops,
>
>I forgot to sort out the catastrophic loss of precision on
>differences. So that
>means that on add and subtract we need to use the maximum fabs value
>of the operands to calculate the rounding trather than the result itself:
>
>So redecimalize() becomes:
>
>double redecimalize(double dval,double rval)
>{
> double f;
> if (dval == 0)
> {
> return dval;
> }
> f = pow(10.0, (double) DBL_DIG - (1 + floor(log10(fabs(rval)))));
> return (double) (rint(dval*f))/f;
> }
>
>
>and add_function, div_function need to look more like:
>
>double dop1,dop2,rval;
>....
> if ((op1->type == IS_DOUBLE || op1->type == IS_LONG)
> && (op2->type == IS_LONG || op2->type == IS_DOUBLE)) {
> dop1 = (op1->type == IS_LONG) ? ((double) op1->value.lval):op1->value.dval;
> dop2 = (op2->type == IS_LONG) ? ((double) op2->value.lval):op2->value.dval;
> result->value.dval = dop1 - dop2;
> rval = fabs(dop1) > fabs(dop2) ? dop1:dop2;
> result->value.dval = redecimalize(result->value.dval,rval);
> result->type = IS_DOUBLE;
> return SUCCESS;
> }
>
>The calls to redecimalize on mul_function,div_function simply pass the
>result twice e.g.
> result->value.dval = redecimalize(result->value.dval,result->value.dval);
>
>There's no significant impact on performance.
>
>George
>
>
>
>
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