[Mapserver-dev] Floating point precision problem in the WMS module

[Jean-Henry Berevoescu]

For one: I see a problem with this when I try to align 6' (or less)
imagery with a layer of vectors (streets for example).

And yes, I tried strtold too (when I tried the lesser strtod).
(I run on Mandrake 10 - but I don't think that should be an
issue. After all Mandrake is a Linux and it originally started
as an RH clone)

Jean


Sean Gillies wrote:

> 11 decimal places? What are you doing, Dermatology? :)
> Did you try strtold (long double)?
>
> According to my standard C library (on BSD), atof is not thread safe
> and has been deprecated in favor of strtod. That was news to me. No
> mention of deprecation on my Linux system (RH9).
>
> Sean
>
> On May 24, 2004, at 4:40 AM, Jean-Henry Berevoescu wrote:
>
>>
>> Hi,
>> I am experiencing a problem in the WMS module and I wonder
>> if there is are others who know about it.
>> Accessing MMS as a WMS Server the request gets parsed in
>> mapwms.c: msWMSLoadGetMapParams(...)
>>
>> ....
>> map->extent.minx = atof(tokens[0]);
>> map->extent.miny = atof(tokens[1]);
>> map->extent.maxx = atof(tokens[2]);
>> map->extent.maxy = atof(tokens[3]);
>> ....
>>
>> I send the WMS request with a BBOX having 10-11 digits after the decimal
>> points for the coordinates. Just before this part of the code I added 
>> a log
>> print and the BBOX coordinates are still all right (altough still as 
>> strings)
>> Doing the same with the value that get into the "extent", I get all the
>> coordinates truncated to 6 digits after the decimal point. It is as if
>> a double gets downsized to a float.
>> The extent structure has doubles so the problem is not that.
>> I also tried to replace "atof" with calls to strod or sscanf and the
>> results are identical.
>>
>> Thanks in advance for any insights on how to solve this problem.
>>
>> Jean
>>
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>>
>
>