# [postgis-users] ST_MaxDistance

George Silva georger.silva at gmail.com
Fri Sep 28 21:33:24 PDT 2012

```I was truly thinking in

SELECT ST_MaxDistance(
ST_MakeLine(ST_MakePoint(0,0),ST_MakePoint(1,1)),
ST_MakeLine(ST_MakePoint(0,0),ST_MakePoint(-1,1)));

I had the extra -1 on y there...sorry for the noise.

On Sat, Sep 29, 2012 at 1:31 AM, George Silva <georger.silva at gmail.com>wrote:

> OMG, I'm sorry,
>
> I've confused the whole thing. I'm awake for a long long time. Way too
> long.
>
> Mathieu, sorry for the trouble.
>
>
> On Sat, Sep 29, 2012 at 1:28 AM, <basille at ase-research.org> wrote:
>
>> Not weird for me: the max distance is between (1,1) and (-1,-1), which is
>> sqrt(2^2 + 2^2) = 2.828427
>> At least, that's what Pythagoras told me once :)
>>
>> Mathieu.
>>
>>
>> Le 28/09/2012 23:58, George Silva a écrit :
>>
>>> Hey guys, weird results here...
>>>
>>> Check this:
>>>
>>> SELECT ST_MaxDistance(
>>> ST_MakeLine(ST_MakePoint(0,0),**ST_MakePoint(1,1)),
>>> ST_MakeLine(ST_MakePoint(0,0),**ST_MakePoint(-1,-1)));
>>> -- 2.82842712474619 (this corresponds to 2x sqrt(2)?)
>>>
>>> For me the max distance between these polylines is 2.
>>>
>>> Or am I expecting something diferent for this function?
>>>
>>> Thanks
>>>
>>> --
>>> George R. C. Silva
>>>
>>> Desenvolvimento em GIS
>>> http://geoprocessamento.net
>>> http://blog.geoprocessamento.**net <http://blog.geoprocessamento.net>
>>>
>>>
>>>
>>> ______________________________**_________________
>>> postgis-users mailing list
>>> postgis-users at postgis.**refractions.net<postgis-users at postgis.refractions.net>
>>> http://postgis.refractions.**net/mailman/listinfo/postgis-**users<http://postgis.refractions.net/mailman/listinfo/postgis-users>
>>>
>>
>> --
>>
>> ~\$ whoami
>> Mathieu Basille, Post-Doc
>>
>> ~\$ locate
>> Laboratoire d'Écologie Comportementale et de Conservation de la Faune
>> + Centre d'Étude de la Forêt
>> Département de Biologie
>> Université Laval, Québec
>>
>> ~\$ info
>> http://ase-research.org/**basille <http://ase-research.org/basille>
>>
>> ~\$ fortune
>> ``If you can't win by reason, go for volume.''
>> Calvin, by Bill Watterson.
>>
>
>
>
> --
> George R. C. Silva
>
> Desenvolvimento em GIS
> http://geoprocessamento.net
> http://blog.geoprocessamento.net
>
>

--
George R. C. Silva

Desenvolvimento em GIS
http://geoprocessamento.net
http://blog.geoprocessamento.net
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