| Re: How can I add parameter to curvefit? [message #5301] |
Wed, 15 November 1995 00:00 |
rivers
Messages: 228
Registered: March 1991
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Senior Member |
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In article <4832k1$37f@decaxp.harvard.edu>, kkobayas@scws40.harvard.edu (Ken Kobayashi) writes:
>
> Hi,
>
> I'm doing a curve fitting using CURVEFIT. However, I would like to be
> able to pass on an extra paremeter to the function that CURFEFIT calls.
> (i.e. the one that returns the function I'm trying to fit to and its
> derivative.) In other words, if the function has three parameters, do a
> least-square fit using just two of the parameters. The only ways I could
> think of were (a) hack CURVEFIT.PRO to add a parameter to the function
> calls, or (b) save the parameter in a file and read that. (a) has a
> problem with portability, and (b) seems rather slow considering the
> function is called many tims. Is there a better way to do this?
>
Use common blocks to communicate the information between your program which
calls CURVEFIT and your evaluation function.
____________________________________________________________
Mark Rivers (312) 702-2279 (office)
CARS (312) 702-9951 (secretary)
Univ. of Chicago (312) 702-5454 (FAX)
5640 S. Ellis Ave. (708) 922-0499 (home)
Chicago, IL 60637 rivers@cars3.uchicago.edu (Internet)
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| Re: How can I add parameter to curvefit? [message #5308 is a reply to message #5301] |
Tue, 14 November 1995 00:00  |
hahn
Messages: 108
Registered: November 1993
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Senior Member |
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kkobayas@scws40.harvard.edu (Ken Kobayashi) wrote:
> Hi,
> I'm doing a curve fitting using CURVEFIT. However, I would like to be
> able to pass on an extra paremeter to the function that CURFEFIT calls.
> (i.e. the one that returns the function I'm trying to fit to and its
> derivative.)
[snip]
There is no problem with portability esp. if you change the name
of the procedure to keep the original.
The other idea, to save the parameter in a file, will only be helpful
when you need this for some other reason (log file).
You may save the parameter in a common block. Although common
blocks are not loved by those programmers who favour structured
programming, this feature is well implemented in IDL and can be used
quite efficiently. BTW it's a lot faster to access variables via
common rather than passing structures via a parameter list!
> - Ken
> --
> ------------------------------------------------------------ -----------------
> Ken Kobayashi . "Too low they build, who build
> kkobayashi@cfa.harvard.edu . beneath the stars."
> http://stargazer.student.harvard.edu/ . - Edward Young
Norbert Hahn
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| Re: How can I add parameter to curvefit? [message #5310 is a reply to message #5308] |
Tue, 14 November 1995 00:00 |
thompson
Messages: 584
Registered: August 1991
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Senior Member |
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kkobayas@scws40.harvard.edu (Ken Kobayashi) writes:
> Hi,
> I'm doing a curve fitting using CURVEFIT. However, I would like to be
> able to pass on an extra paremeter to the function that CURFEFIT calls.
> (i.e. the one that returns the function I'm trying to fit to and its
> derivative.) In other words, if the function has three parameters, do a
> least-square fit using just two of the parameters. The only ways I could
> think of were (a) hack CURVEFIT.PRO to add a parameter to the function
> calls, or (b) save the parameter in a file and read that. (a) has a
> problem with portability, and (b) seems rather slow considering the
> function is called many tims. Is there a better way to do this?
You can always use a common block to pass additional information to the fitted
function.
Bill Thompson
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