I had written a C program and if I remember right, I typed the constants
as integers instead of floats, that means something like
...(24*pow(cos(...
instead of
...(24.0*pow... .
And therefore the compiler did some type conversion magic.
Manfred
Janeks Kamerovskis schrieb:
It is Rebol scripting language and there are only integers and decimals that
is based on 64-bit standard IEEE floating point numbers. Is it enought for
these formulas?
Could you plese send more information about how you find solution un your
case.
Janeks
-----Original Message-----
From: UMN MapServer Users List [mailto:[EMAIL PROTECTED] On
Behalf Of Manfred Meier
Sent: Saturday, February 11, 2006 6:19 AM
To: [email protected]
Subject: Re: [UMN_MAPSERVER-USERS] coordinate transformations formulas ...
?
Hello,
I had a similar problem. What programming language do you use? I had
trouble with some double to float or double to long conversion (done by
the compiler) because i declared some variables not appropriate.
Manfred
Janeks Kamerovskis schrieb:
Yes and I tested, that I can safely ignore those ..., because they have
realy small influence on result.
But the next problem is that I can get those example value for M an M0.
They
are sligtly different for the given example (from EPSG quidance
http://www.epsg.org/guides/docs/G7-2.pdf) it differs by some cople of
thousands (5596050.46000000 5602234.40780535 and 5429228.60000000
5435961.03820551)
I checked many of the sources of Transverse Mercator formulas
description
(EPSG of course and other) they all looked the same.
I checked my implementations of formulas not only twice, but the result
is
the same.
Janeks
P.S. Sorry about looking like offtopic - you could ask why I need to
implement things that already has in proj4. I just have a case, when it
is
difficult to use, but finaly data any way will come to Mapserver.
-----Original Message-----
From: UMN MapServer Users List [mailto:[EMAIL PROTECTED] On
Behalf Of Stephen Woodbridge
Sent: Wednesday, February 08, 2006 5:00 PM
To: [email protected]
Subject: Re: [UMN_MAPSERVER-USERS] coordinate transformations formulas
...
?
The ... means "and additional terms following the sequence of the prior
terms". It is basically a short hand notation for a summation of n to
infinity. So you if you want more terms you need to first infer the
sequence from the prior terms like [2, 4, 6, ...] is a sequence and the
next terms are 8, 16, 32, ...
Each additional term adds some additional fractional accuracy to the
computation, at some point the fractional accuracy is beyond the point
that it is significant to to our uses.
If you calculate just the 3rd term and see how big its value is it will
give you the magnitude of the change it is impacting on the equation and
the next term in the sequence will tern to be significantly smaller.
-Steve W.
Janeks Kamerovskis wrote:
Hi list,
What means those ... in the formula, that is part of coordinate
transformations formulas?
M = a[(1 - e2/4 - 3e4/64 - 5e6/256 -....)j - (3e2/8 + 3e4/32 +
45e6/1024+....)sin2j + (15e4/256 + 45e6/1024 +.....)sin4j - (35e6/3072
+
....)sin6j + .....]
brgds
Janeks
