Using part of output of an expression as a input of another expression
Subject: Using part of output of an expression as a input of another expression
From: Stavros Macrakis
Date: Fri, 8 Jan 2010 09:50:45 -0500
subst(lambda([a,b,c,d],a),nounify('sum),%o11);
On Thu, Jan 7, 2010 at 3:18 AM, Cuneyt Ertal <cuneyt.ertal at gmail.com> wrote:
> Hi I am a newbie maxima user. I want to use part of an output expression as
> a input of another expression.
>
>
> (%i3) w(x,t):=sum(w[n](t)*sin(n*%pi*x),n,0,inf);
> (%o3) w(x,t):=sum(w[n](t)*sin(n*%pi*x),n,0,inf)
> (%i4) diff(w(x,t),x);
> (%o4) %pi*sum(n*w[n](t)*cos(%pi*n*x),n,0,inf)
> (%i5) diff(w(x,t),x,2);
> (%o5) -%pi^2*sum(n^2*w[n](t)*sin(%pi*n*x),n,0,inf)
> (%i6) diff(w(x,t),x,3);
> (%o6) -%pi^3*sum(n^3*w[n](t)*cos(%pi*n*x),n,0,inf)
> (%i7) diff(w(x,t),x,4);
> (%o7) %pi^4*sum(n^4*w[n](t)*sin(%pi*n*x),n,0,inf)
> (%i8) diff(w(x,t),t,2);
> (%o8) sum(('diff(w[n](t),t,2))*sin(%pi*n*x),n,0,inf)
> (%i9) f(x,t):=sum(f[n](t)*sin(n*%pi*x),n,0,inf);
> (%o9) f(x,t):=sum(f[n](t)*sin(n*%pi*x),n,0,inf)
> (%i10) diff(f(x,t),x,2);
> (%o10) -%pi^2*sum(n^2*f[n](t)*sin(%pi*n*x),n,0,inf)
> (%i11) diff(w(x,t),x,4)+diff(w(x,t),t,2)=sum(f[n](t)*sin(n*%pi*x),n,0,inf);
> (%o11)
> (sum(('diff(w[n](t),t,2))*sin(%pi*n*x),n,0,inf))+%pi^4*sum(n^4*w[n](t)*sin(%pi*n*x),n,0,inf)=sum(f[n](t)*sin(%pi*n*x),n,0,inf)
>
> i want to use %o11 without sums , like this;
>
>
> 'diff(w[n](t),t,2)*sin(%pi*n*x)+%pi^4*(n^4*w[n](t)*sin(%pi*n*x)=f[n](t)*sin(%pi*n*x)
>
> How can I do that?
>
> --
> Cuneyt Ertal.
>
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>