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Re: A complicate problem for building a map [message #36768 is a reply to message #36690]

Thu, 16 October 2003 16:36

condor
Messages: 35
Registered: January 2002

Member

ftls1@uaf.edu (ftls1@uaf.edu) wrote in message news:<44042ede.0310150951.71dad28a@posting.google.com>...
> I met a problem of map building as below,
> I have two 2-D tables of RT(nw,nt), RW(nw,nt), nw and nt are
> constants,

i.e. not variables. OK.

Are RT and RW unique? I.e. can there be values in these tables that
appear more than once.

E.g. is it possible that RT[3,5] = RT[10,15]

> both RT and RW range from -1 to +1,

What is the meaning of these numbers? In particular: what is the
granularity? Are we talking three possible values (-1,0,1) or many
many values?

> the value of nw, even though it is
> 'integer',actually means wind speed from
> -50 m/s to 50 m/s and the nt means temperature from 0 to 300 K.

Speaking only for myself, at this point you're confusing me. Are they
constant or are they variable? When you say "0 to 300K" then you seem
to imply that there's more than one possibility

> Now I want to get a table with x and y axis of RT and RW respectively.
> The purpose to build such a table is that if there is an arbitrary
> pair of RW and RT value, I can look it in the table and find the
> appropriate wind and temperature.

But what would be the "appropriate" wind and temperature?

Obviously you can create an array where RT and RW are the
(appropriately scaled) indices. Call it "A". Then you could do
something like

A[(RT+1)/n,(RW+1)/n]

but from the given information it is not clear what should be written
in this array at that location. If various different values of nw and
nt can produce the same RT and/or RW values, which of them are the
"appropriate" ones to store at that location?

> I've been thinking on this topic for a couple of weeks without any
> idea, in C language there is a concept of 'Group', but IDL does not.

Unfortunately my understanding of C is on the basic side, and I don't
think I have ever heard of a "group" in C, so I don't know what
functionality you are looking for. Can you describe what that is
supposed to do and maybe someone could tell you how to emulate this in
IDL.

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[Message index]

		A complicate problem for building a map By: ftls1 on Wed, 15 October 2003 10:51
		Re: A complicate problem for building a map By: ftls1 on Tue, 21 October 2003 15:02
		Re: A complicate problem for building a map By: Olaf Stetzer on Tue, 21 October 2003 00:33
		Re: A complicate problem for building a map By: condor on Mon, 20 October 2003 15:49
		Re: A complicate problem for building a map By: ftls1 on Mon, 20 October 2003 14:52
		Re: A complicate problem for building a map By: Olaf Stetzer on Mon, 20 October 2003 04:42
		Re: A complicate problem for building a map By: ftls1 on Sat, 18 October 2003 23:23
		Re: A complicate problem for building a map By: condor on Thu, 16 October 2003 16:36

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