Re: VisAD memory and speed performace with large data set / etc

  • To: m huang <qomo@xxxxxxxxx>
  • Subject: Re: VisAD memory and speed performace with large data set / etc
  • From: Bill Hibbard <billh@xxxxxxxxxxxxx>
  • Date: Sat, 14 Dec 2002 15:52:10 -0600 (CST)
Hi Maohai,

> Thanks for the clarification. I saw this in
> ...
>    * @param  copy    flag to copy values - meaningless for FlatField
>    * ...
>    */
>   public void setSample(int index, Data range, boolean copy)
> ...
> I wondered if the VisAD developers meant this to be copy
> was "meaningless" everywhere in FlatField. JavaDoc of
> setSamples(double[][] range, boolean copy) does say "copy array
> if copy flag is true", but after seeing the "meaningless" clause,
> I thought I should get an confirmation from you guys that "do
> not copy array if copy flag is not true"! Sorry to be so fussy
> but I think it's prudent to regard the documentation as the
> only "legal" contract between the API developer and the API users.

The copy flag is meaningful for same signature of setSample()
for FlatField's parent class FieldImpl. FlatField needs to
override the implementation, but in this case the copy flag
is meaningless.

> I attended Herschel IA working group meeting last
> week. We need to decide on the software framework early next
> year. That is the next milestone, after which the framework of
> IA is largely frozen. Because the people who evaluated VisAD
> found VisAD was difficult to understand and more so even to make
> a prototype, a Herschel IA dataSet frame work is proposed without
> structural consideration to use VisAD, yet it has abstract data model
> that supports array of tuples, unit conversion, error propagation,
> can be plotted in "layers" etc etc...  lots of what VisAD excels
> in doing. This makes me wonder how many more projects out there
> are trying to reinvent VisAD because they couldn't understand
> what's already in VisAD.

There was a guy in the early days of VisAD who claimed he
couldn't understand the data model, then developed his own
system with an identical data model (the class names had
been changed). This stuff is very amusing.

> Because no one in the meeting really understandd VisAD much,
> with my best effort I could only persuade my colleagues to send
> me some key requirement for Herschel IA and I will tell them,
> as best as I can, if/how these requirement can be met by using
> VisAD, in the next month.  Then based on that we will re-evaluate
> our situation. If anyone thinks I could better RTFM befor asking
> some of my questions in the list, I appologize. I have a
> short time line to "sell" VisAD.
> I also persuaded some of my colleagues to take a closer look at
> VisAD at the same time, and encourage them to ask questions here.

Thanks for your support, and good luck.


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