From: Kristof Bastiaensen <kristof@...>
Date: 2004-09-02T04:55:32+09:00
Subject: Re: invisible Infinity

On Thu, 02 Sep 2004 04:25:57 +0900, Mohammad Khan wrote:

> On Wed, 2004-09-01 at 15:22, Mohammad Khan wrote:
>> If you take a look in numeric.c
>> 
>> 
>> /*
>>  *  call-seq:
>>  *     flt.to_s    => string
>>  *
>>  *  Returns a string containing a representation of self. As well as a *
>>   fixed or exponential form of the number, the call may return * 
>>  ``<code>NaN</code>'', ``<code>Infinity</code>'', and * 
>>  ``<code>-Infinity</code>''.
>>  */
>>                                                                                                                                                              
>> static VALUE
>> flo_to_s(flt)
>>     VALUE flt;
>> {
>>     char buf[32];
>>     char *fmt = "%.15g";
>>     double value = RFLOAT(flt)->value;
>>     double avalue, d1, d2;
>>                                                                                                                                                              
>>     if (isinf(value))
>>         return rb_str_new2(value < 0 ? "-Infinity" : "Infinity");
>>     else if(isnan(value))
>>         return rb_str_new2("NaN");
>>                                                                                                                                                              
>>     avalue = fabs(value);
>>     if (avalue == 0.0) {
>>         fmt = "%.1f";
>>     }
>>     else if (avalue < 1.0e-3) {
>>         d1 = avalue;
>>         while (d1 < 1.0) d1 *= 10.0;
>>         d1 = modf(d1, &d2);
>>         if (d1 == 0) fmt = "%.1e";
>>     }
>>     else if (avalue >= 1.0e15) {
>>         d1 = avalue;
>>         while (d1 > 10.0) d1 /= 10.0;
>>         d1 = modf(d1, &d2);
>>         if (d1 == 0) fmt = "%.1e";
>>         else fmt = "%.16e";
>>     }
>>     else if ((d1 = modf(value, &d2)) == 0) {
>>         fmt = "%.1f";
>>     }
>>     sprintf(buf, fmt, value);
>>                                                                                                                                                              
>>     return rb_str_new2(buf);
>> }
>> }
>> Infinity and -Infinity is String and it is just a representation. It is
>> definitely, not a Constant.
>> 
>> I am wrong, correct me please.
> 
> I meant,
> If I am wrong, correct me please.
> 

I am not sure if this is what you meant, but Infinity is not a string:

(10.0/0).class
=> Float

(10.0/0).to_s.class
=> String

Regards,
KB