f & g are output formatting codes, f is the normal double-precision
format, while g produces scientific notation (mmmE+xx) if the number
is < 0.0001. The 8 and 15 represent the number of significant digits
to print (for g).
-- Andy
On May 16, 2008, at 3:33 PM, Obe, Regina wrote:
First I can't remember what g means. I remember seeing fs and gs
somewhere before so I can only assume that f means round and g means
truncate?
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
Paul
Ramsey
Sent: Friday, May 16, 2008 10:39 AM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] Does ST_AsText truncate or round
It all falls down into this function:
write_double(double val){
ensure(32);
if (lwgi)
sprintf(out_pos,"%.8g",val);
else
sprintf(out_pos,"%.15g",val);
to_end();
}
On Fri, May 16, 2008 at 3:23 AM, Paragon Corporation <[EMAIL PROTECTED]>
wrote:
Slight clarification about what I am trying to solve.
After edits I am coming back with lines that used to be intersecting
no
longer intersecting and that still have the same AsText
representation.
My hope is to reduce the precision of my geometry in the database so
the
edits don't break the topology of my lines by doing something like
this
Update sometable
SET the_geom = ST_SetSRID(ST_AsText(the_geom), mysrid)
But I fear that if AsText is doing a rounding rather than a
truncation, that
I run the risk of breaking things that used to intersect. I am more
concerned about under intersecting than over intersecting.
Although I
probably haven't thought this out enough so maybe it's a non-issue.
Thanks,
Regina
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
Paragon
Corporation
Sent: Friday, May 16, 2008 12:01 AM
To: 'PostGIS Users Discussion'
Subject: [postgis-users] Does ST_AsText truncate or round
Hopefully this is a simple question. I know that ST_AsText returns a
geometry that is not necessarily as prescise as what is actually
stored in
the geometry field. I have an editor that relies on WKT
representation.
Anyrate just wanted to know if the ST_AsText does a rounding of the
points
or it does a truncation of the points. Also would be nice to know if
I
could control the precision of this since I will need to truncate my
actual
geometry accordingly so that both are in agreement.
Thanks,
Regina
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