| Re: Plot according to slopes? [message #60195] |
Mon, 05 May 2008 09:07 |
Frank Wang
Messages: 6
Registered: May 2008
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Junior Member |
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On May 5, 11:19 pm, David Fanning <n...@dfanning.com> wrote:
> Frank Wang writes:
>> Thank you, David. But would you tell me where to download PARVELVECT(I
>> searched it over google, but got no result)?
>
> You searched for "NASA IDL Astronomy Library" and got no result!?
> Weird.
>
> Cheers,
>
> David
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming:http://www.dfanning.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
Thank you for help, David. But I guess what you meant is PARTVELVECT,
not PARVELVECT? I found the former in the NASA Lib. Anyway, thank you
for help!!!!
Best Regards,
Frank
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| Re: Plot according to slopes? [message #60196 is a reply to message #60195] |
Mon, 05 May 2008 09:05  |
Frank Wang
Messages: 6
Registered: May 2008
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Junior Member |
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On May 5, 11:19 pm, David Fanning <n...@dfanning.com> wrote:
> Frank Wang writes:
>> Thank you, David. But would you tell me where to download PARVELVECT(I
>> searched it over google, but got no result)?
>
> You searched for "NASA IDL Astronomy Library" and got no result!?
> Weird.
>
> Cheers,
>
> David
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming:http://www.dfanning.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
Thank you for reply, David. But maybe you mean PARTVELVEC, rather than
PARVELVECT?
Anyway, thank you for help!
Regards,
Frank
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| Re: Plot according to slopes? [message #60197 is a reply to message #60196] |
Mon, 05 May 2008 08:19 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Frank Wang writes:
> Thank you, David. But would you tell me where to download PARVELVECT(I
> searched it over google, but got no result)?
You searched for "NASA IDL Astronomy Library" and got no result!?
Weird.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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| Re: Plot according to slopes? [message #60198 is a reply to message #60197] |
Mon, 05 May 2008 08:17 |
Frank Wang
Messages: 6
Registered: May 2008
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Junior Member |
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On May 5, 10:57 pm, ri...@crd.ge.com wrote:
> On May 5, 9:43 am, Frank Wang <Muchi0...@gmail.com> wrote:
>
>> "How to make line plot when you know the slopes(of the lines you are
>> going to plot) defined at each grid point"?
>
> How about integrating your slopes numerically, then plotting the
> integral? It sounds like you've got df/dx on a regular grid. If so,
> then f(x) is approximately dx * total(df/dx, /cumulative) + constant,
> where dx is the grid spacing. One value of f(x) gives you the
> constant, if you care about it. There are better integration methods,
> if you need to get fancier.
>
> --Wayne
Thank you for reply. I think your suggenstion is good, and I will try
to integrate it. Thank you.
Regards,
Frank
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| Re: Plot according to slopes? [message #60199 is a reply to message #60198] |
Mon, 05 May 2008 07:57 |
rigby
Messages: 16
Registered: September 1995
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Junior Member |
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On May 5, 9:43 am, Frank Wang <Muchi0...@gmail.com> wrote:
> "How to make line plot when you know the slopes(of the lines you are
> going to plot) defined at each grid point"?
How about integrating your slopes numerically, then plotting the
integral? It sounds like you've got df/dx on a regular grid. If so,
then f(x) is approximately dx * total(df/dx, /cumulative) + constant,
where dx is the grid spacing. One value of f(x) gives you the
constant, if you care about it. There are better integration methods,
if you need to get fancier.
--Wayne
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| Re: Plot according to slopes? [message #60200 is a reply to message #60199] |
Mon, 05 May 2008 07:46 |
Frank Wang
Messages: 6
Registered: May 2008
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Junior Member |
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On May 5, 10:00 pm, David Fanning <n...@dfanning.com> wrote:
> Frank Wang writes:
>> I am new with IDL, and recently I was bothered with:
>
>> "How to make line plot when you know the slopes(of the lines you are
>> going to plot) defined at each grid point"?
>
>> Physically, we can draw a short line segment at each grid point, link
>> neighboring segments, and then smooth them. But I simply find it too
>> tricky to do this with ID(or Matlab). Does anyone have any
>> suggestions? I would appreciate your help. Or you can tell me which
>> chapter of the IDL manual should I refer to?
>
> I guess if you knew the slopes at each point, you could
> calculate UV vector pairs that would describe the slope.
> If so, then you could use something like VELOVECT or
> PLOT_FIELD to plot them. A lot of people use PARVELVECT
> from the NASA Astronomy Library to plot this kind of data,
> too.
>
> Cheers,
>
> David
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming:http://www.dfanning.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
Thank you, David. But would you tell me where to download PARVELVECT(I
searched it over google, but got no result)?
Thank you again for help.
Cheers,
Frank
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| Re: Plot according to slopes? [message #60201 is a reply to message #60200] |
Mon, 05 May 2008 07:00 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Frank Wang writes:
> I am new with IDL, and recently I was bothered with:
>
> "How to make line plot when you know the slopes(of the lines you are
> going to plot) defined at each grid point"?
>
> Physically, we can draw a short line segment at each grid point, link
> neighboring segments, and then smooth them. But I simply find it too
> tricky to do this with ID(or Matlab). Does anyone have any
> suggestions? I would appreciate your help. Or you can tell me which
> chapter of the IDL manual should I refer to?
I guess if you knew the slopes at each point, you could
calculate UV vector pairs that would describe the slope.
If so, then you could use something like VELOVECT or
PLOT_FIELD to plot them. A lot of people use PARVELVECT
from the NASA Astronomy Library to plot this kind of data,
too.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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