Subject: How to graph an expression involving sum?
From: Stavros Macrakis
Date: Sat, 10 Sep 2011 16:54:18 -0400
I left out the subst, sorry.
On Sep 10, 2011 8:59 AM, "Stavros Macrakis" <macrakis at alum.mit.edu> wrote:
> I would suggest defining a function in expanded form then compiling it:
>
> myfun(x) := ( mode_declare(x,float), ''(ev(coefseries,nouns)) ) $
> (that's two single-quotes, not one double-quote)
> compile(myfun)$
> plot2d( myfun, ... )
>
> It would also be possible to convert the sum into a loop and the a[i]=
into
> a[i]:, but that is more work for the same result.
>
> -s
>
> On Thu, Sep 8, 2011 at 16:36, dlakelan <dlakelan at street-artists.org>
wrote:
>
>> On 09/05/2011 01:08 PM, dlakelan wrote:
>> > I have a solution of a differential equation in terms of some fourier
>> > series. I would like to graph one of the spatially varying
coefficients,
>> > so I tried something like:
>> ....
>> > What's the right way to go about graphing something like this?
>>
>> I should mention that I can do ev(coefseries,nouns) to convert the "sum"
>> noun into an enormous + expression, but this slows things down
>> considerably. If I am trying to simply do numerical calculations with
>> the expression, is there a faster way to get the evaluation than to
>> carry around a big symbolic expression? Is something like a lambda
>> expression like this the way to go?
>>
>> lambda([x],ev(coefseries,avals,nouns,z=x,numer))
>>
>> or does this just internally create and throw away the enormous +
>> expression?
>>
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