I don't understand why I'm getting an 'inf' by raising E to a real number, e^^710.0L. See below.

import std.stdio;
import std.math;

unittest
{
	writefln("ln(largest double) = %s", log(double.max)); // 709.783
	writefln("e^710 = %s", exp(710.0));// inf, makes sense

	writefln("ln(largest real) = %s", log(real.max)); // 11356.6
	real t = 710.0;
	writefln("e^710 = %s", exp(t)); //why is this inf???
}

Any help would be greatly appreciated. I have functions in an actual program that are giving me a headache due to this issue.

On Wednesday, 7 March 2018 at 15:44:28 UTC, Matt Gamble wrote:
> I don't understand why I'm getting an 'inf' by raising E to a real number, e^^710.0L. See below.
>
> import std.stdio;
> import std.math;
>
> unittest
> {
> 	writefln("ln(largest double) = %s", log(double.max)); // 709.783
> 	writefln("e^710 = %s", exp(710.0));// inf, makes sense
>
> 	writefln("ln(largest real) = %s", log(real.max)); // 11356.6
> 	real t = 710.0;
> 	writefln("e^710 = %s", exp(t)); //why is this inf???
> }
>
> Any help would be greatly appreciated. I have functions in an actual program that are giving me a headache due to this issue.

works for me as expected.

ln(largest double) = 709.783
e^710 = inf
ln(largest real) = 11356.5
e^710 = 2.23399e+308

On Wednesday, 7 March 2018 at 16:00:39 UTC, Alex wrote:
> On Wednesday, 7 March 2018 at 15:44:28 UTC, Matt Gamble wrote:
>> I don't understand why I'm getting an 'inf' by raising E to a real number, e^^710.0L. See below.
>>
>> import std.stdio;
>> import std.math;
>>
>> unittest
>> {
>> 	writefln("ln(largest double) = %s", log(double.max)); // 709.783
>> 	writefln("e^710 = %s", exp(710.0));// inf, makes sense
>>
>> 	writefln("ln(largest real) = %s", log(real.max)); // 11356.6
>> 	real t = 710.0;
>> 	writefln("e^710 = %s", exp(t)); //why is this inf???
>> }
>>
>> Any help would be greatly appreciated. I have functions in an actual program that are giving me a headache due to this issue.
>
> works for me as expected.
>
> ln(largest double) = 709.783
> e^710 = inf
> ln(largest real) = 11356.5
> e^710 = 2.23399e+308

Really? Is it my system?
I'm running windows 10, with an intel Core i7-4650, 64bit operating system
I compiled with -m64 -g -unittest -main

On Wednesday, 7 March 2018 at 16:00:39 UTC, Alex wrote:
> On Wednesday, 7 March 2018 at 15:44:28 UTC, Matt Gamble wrote:
>> I don't understand why I'm getting an 'inf' by raising E to a real number, e^^710.0L. See below.
>>
>> import std.stdio;
>> import std.math;
>>
>> unittest
>> {
>> 	writefln("ln(largest double) = %s", log(double.max)); // 709.783
>> 	writefln("e^710 = %s", exp(710.0));// inf, makes sense
>>
>> 	writefln("ln(largest real) = %s", log(real.max)); // 11356.6
>> 	real t = 710.0;
>> 	writefln("e^710 = %s", exp(t)); //why is this inf???
>> }
>>
>> Any help would be greatly appreciated. I have functions in an actual program that are giving me a headache due to this issue.
>
> works for me as expected.
>
> ln(largest double) = 709.783
> e^710 = inf
> ln(largest real) = 11356.5
> e^710 = 2.23399e+308

it works for me too.

https://imgur.com/bLGTv1l

On Wednesday, 7 March 2018 at 16:06:26 UTC, Matt Gamble wrote:
> On Wednesday, 7 March 2018 at 16:00:39 UTC, Alex wrote:
>> On Wednesday, 7 March 2018 at 15:44:28 UTC, Matt Gamble wrote:
>>> [...]
>>
>> works for me as expected.
>>
>> ln(largest double) = 709.783
>> e^710 = inf
>> ln(largest real) = 11356.5
>> e^710 = 2.23399e+308
>
> Really? Is it my system?
> I'm running windows 10, with an intel Core i7-4650, 64bit operating system
> I compiled with -m64 -g -unittest -main

Did notice you were using -m64 flag before. Well, now I used -m64 the same code doesn't work as expected. I also got inf.

On Wednesday, 7 March 2018 at 16:10:15 UTC, Marc wrote:
> On Wednesday, 7 March 2018 at 16:00:39 UTC, Alex wrote:
>> On Wednesday, 7 March 2018 at 15:44:28 UTC, Matt Gamble wrote:
>>> [...]
>>
>> works for me as expected.
>>
>> ln(largest double) = 709.783
>> e^710 = inf
>> ln(largest real) = 11356.5
>> e^710 = 2.23399e+308
>
> it works for me too.
>
> https://imgur.com/bLGTv1l

Wow, Now I'm really confused, I'm using DMD v2.076.1. Any thoughts I why I'm getting this result?

On Wednesday, 7 March 2018 at 16:12:28 UTC, Matt Gamble wrote:
> On Wednesday, 7 March 2018 at 16:10:15 UTC, Marc wrote:
>> On Wednesday, 7 March 2018 at 16:00:39 UTC, Alex wrote:
>>> On Wednesday, 7 March 2018 at 15:44:28 UTC, Matt Gamble wrote:
>>>> [...]
>>>
>>> works for me as expected.
>>>
>>> ln(largest double) = 709.783
>>> e^710 = inf
>>> ln(largest real) = 11356.5
>>> e^710 = 2.23399e+308
>>
>> it works for me too.
>>
>> https://imgur.com/bLGTv1l
>
> Wow, Now I'm really confused, I'm using DMD v2.076.1. Any thoughts I why I'm getting this result?

See my previous post. It's something related to generating 64bit code.

On Wednesday, 7 March 2018 at 16:12:28 UTC, Matt Gamble wrote:
> On Wednesday, 7 March 2018 at 16:10:15 UTC, Marc wrote:
>> On Wednesday, 7 March 2018 at 16:00:39 UTC, Alex wrote:
>>> On Wednesday, 7 March 2018 at 15:44:28 UTC, Matt Gamble wrote:
>>>> [...]
>>>
>>> works for me as expected.
>>>
>>> ln(largest double) = 709.783
>>> e^710 = inf
>>> ln(largest real) = 11356.5
>>> e^710 = 2.23399e+308
>>
>> it works for me too.
>>
>> https://imgur.com/bLGTv1l
>
> Wow, Now I'm really confused, I'm using DMD v2.076.1. Any thoughts I why I'm getting this result?

Yes if I switch to 32bit, it works for me now. Is this a bug?

On 3/7/18 11:19 AM, Matt Gamble wrote:
> On Wednesday, 7 March 2018 at 16:12:28 UTC, Matt Gamble wrote:
>> On Wednesday, 7 March 2018 at 16:10:15 UTC, Marc wrote:
>>> On Wednesday, 7 March 2018 at 16:00:39 UTC, Alex wrote:
>>>> On Wednesday, 7 March 2018 at 15:44:28 UTC, Matt Gamble wrote:
>>>>> [...]
>>>>
>>>> works for me as expected.
>>>>
>>>> ln(largest double) = 709.783
>>>> e^710 = inf
>>>> ln(largest real) = 11356.5
>>>> e^710 = 2.23399e+308
>>>
>>> it works for me too.
>>>
>>> https://imgur.com/bLGTv1l
>>
>> Wow, Now I'm really confused, I'm using DMD v2.076.1. Any thoughts I why I'm getting this result?
> 
> Yes if I switch to 32bit, it works for me now. Is this a bug?

Looks like it. The core.stdc.math module looks very cryptic, but appears to do some weird things via exp on real.

-Steve

On Wednesday, 7 March 2018 at 16:40:04 UTC, Steven Schveighoffer wrote:
> On 3/7/18 11:19 AM, Matt Gamble wrote:
>> On Wednesday, 7 March 2018 at 16:12:28 UTC, Matt Gamble wrote:
>>> On Wednesday, 7 March 2018 at 16:10:15 UTC, Marc wrote:
>>>> On Wednesday, 7 March 2018 at 16:00:39 UTC, Alex wrote:
>>>>> [...]
>>>>
>>>> it works for me too.
>>>>
>>>> https://imgur.com/bLGTv1l
>>>
>>> Wow, Now I'm really confused, I'm using DMD v2.076.1. Any thoughts I why I'm getting this result?
>> 
>> Yes if I switch to 32bit, it works for me now. Is this a bug?
>
> Looks like it. The core.stdc.math module looks very cryptic, but appears to do some weird things via exp on real.
>
> -Steve

Thanks. I submitted as a bug. https://issues.dlang.org/show_bug.cgi?id=18570