| Re: A complicate problem for building a map [message #36742 is a reply to message #36690] |
Sat, 18 October 2003 23:23   |
ftls1
Messages: 4
Registered: October 2003
|
Junior Member |
|
|
condor@biosys.net (Big Bird) wrote in message news:<df160b8f.0310161536.3cf83a8a@posting.google.com>...
> 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]
yes,some points have the same value in RT and RW respectively.
>
>> 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?
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
>
e.g. RT[n,k]= #, where # is the value for RT, n and k are variables
for wind speed and temperature functions respectively.
in another word, the # is RT's value is under a secific wind speed
and temperatue condition.
>> 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.
sorry, made a typo. what I said is 'Record' in Pascal Language.
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
