comp.lang.idl-pvwave archive: archive » Amoeba and Tied Parameters

Home » Public Forums » archive » Amoeba and Tied Parameters

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Amoeba and Tied Parameters [message #94081 is a reply to message #94080]

Sat, 14 January 2017 07:43

Dick Jackson
Messages: 347
Registered: August 1998

Senior Member

On Friday, 13 January 2017 20:06:36 UTC-8, Maryam wrote:
> Does anyone know how I can tie two parameters together when using Amoeba so that no matter how much they are changed, they are always equal? In other words, I am looking for something similar to .TIED in MPFIT but when using AMOEBA instead.
>
> Thank you,
> Maryam

Hi Maryam,

If you are minimizing a function of 'n' parameters, and you want to tie one of them to be identical to another one (or computed as a function of another one), then you really only have 'n-1' parameters, making your minimization problem one dimension smaller.

For example, if your function to be minimized were originally computed based on p[0], p[1] and p[2], then you decide to tie p[2] to be equal to p[0], simply replace each p[2] in the function by p[0], and adjust your use of P0, SCALE, SIMPLEX, and the result of FUNCTION_VALUE to work with an 'n' of two rather than three.

Similarly, for example, if you knew that you want to tie p[2] to always be the square root of p[0], in your function you could compute it based on p[0], p[1] and a variable you compute as p2 = Sqrt(p[0]).

I hope this helps you out!

Cheers,
-Dick

Dick Jackson Software Consulting Inc.
Victoria, BC, Canada --- http://www.d-jackson.com

Report message to a moderator

[Message index]

		Amoeba and Tied Parameters By: Maryam on Fri, 13 January 2017 20:06
		Re: Amoeba and Tied Parameters By: Dick Jackson on Sat, 14 January 2017 07:43
		Re: Amoeba and Tied Parameters By: Maryam on Sat, 14 January 2017 10:27
		Re: Amoeba and Tied Parameters By: Maryam on Tue, 17 January 2017 18:21

Previous Topic:	reform a transposed array
Next Topic:	IDL 8.6 demo mode

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Wed Oct 08 18:03:54 PDT 2025

Total time taken to generate the page: 0.00470 seconds