| Re: math [message #73673 is a reply to message #71340] |
Mon, 22 November 2010 11:13   |
Ammar Yusuf
Messages: 36
Registered: October 2010
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Member |
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On Nov 22, 7:04 am, MC <morefl...@gmail.com> wrote:
> There are several routines, search the online help for "differential
> equation"
>
> Here's one from the help:
>
> PRO LSODETEST
>
> ; Define the step size:
> H = 0.5
> ; Define an initial X value:
> X = 0.0
> ; Define initial Y values:
> Y = [4.0, 6.0]
> ; Integrate over the interval (0, 0.5):
> result = LSODE(Y, X, H, 'differential')
>
> ; Print the result:
> PRINT, result
> END
> FUNCTION differential, X, Y
> RETURN, [-0.5 * Y[0], 4.0 - 0.3 * Y[1] - 0.1 * Y[0]]
> END
>
> Note that function can have more parameters passed that can control
> its behaviour, which may be what you are asking for in Q3. I can't
> understand your 2nd and 4th Q's
>
> Cheers MC
>
> On Nov 22, 9:58 am, amin farhang <farhang.a...@gmail.com> wrote:
>
>> dear readers,
>> i have some questions about IDL
>> 1. how can i solve differential equations in IDL? i know that the RK4
>> function do it but it is very obscure, may you introduce a simple
>> method to solve all differential equations?
>> 2. what is the simplest way for taking the integrals directly
>> (specially 1D integrals) without write a function?
>> 3. How do I define a function that its parameters could be changed in
>> every calling (for example in every step of FOR-DO loop, function
>> return a new value)?
>> 4. does functions could return a paramedical equations? if OK how?
>> thank you so much and sorry for my many questions
>> best regards,
>
>
For this
2. what is the simplest way for taking the integrals directly
(specially 1D integrals) without write a function?
You can probably use the total function. I'm pretty sure that
would be the easiest.
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