[GRASS-user] log function for SQLite

[Nikos Alexandris]

NikosAlexandris wrote:

>>>>> Dear list,
>>>>>
>>>>> where is the extension for SQLite that contains the (mathematical) log
>>>>> function available to download?  As referenced in
>>>>> https://grass.osgeo.org/grass73/manuals/v.db.update.html.

Helmut Kudrnovsky:

>>>>> I think the reference in the manual requires a source or a link to it.
>>>>
>>>> just found something in the wiki:
>>>>
>>>> https://grasswiki.osgeo.org/wiki/Build_SQLite_extension_on_windows

Nikos:

>> For Linux:
>>
>> gcc extension-functions.c -fPIC -shared -o libextensionfunctions.so
>>
>> Note,
>>
>> 1) there is still a "compile" warning for the code (no time to hunt)
>> 2) The log() function does not like, naturally, 0 values. But this can
>> be workedaround with a where SQL clause.
>>
>> Can we not integrate this into GRASS?  It feels awkward to have to spend
>> so much time for a log or similar function to use in a v.db.update call.

Moritz:

>-1
>
>I don't think we should start interalizing solutions to issues related
>to database backend choice.

We can of course integrate a log and an "sqrt" function for v.db.update,
right?

Nikos