Fwd: [maxima - Help] FEM Weak form & Maxima (Integration by Parts)
Subject: Fwd: [maxima - Help] FEM Weak form & Maxima (Integration by Parts)
From: Robert Dodier
Date: Sat, 8 Apr 2006 10:00:47 -0600
ck,
> > /* Why cant Macsyma do integration by parts? */
well, i dunno.
the only function which i can find related to integration
by parts is this one-liner,
byparts(exp,x,u,dv):=(dv:integrate(dv,x),u*dv-integrate(dv*diff(u,x,1),x));
(in share/integration/bypart.mac).
> 2) Once you have the weak form, it would be nice to have Maxima
> generate the stiffness matrices as well... but the following chunk fails.
> N1(x):= ((x-x2)*(x-x3)) / ((x1-x2)*(x1-x3))$
> N2(x):= ((x-x1)*(x-x3)) / ((x2-x1)*(x2-x3))$
> N3(x):= ((x-x1)*(x-x2)) / ((x3-x1)*(x3-x2))$
> dN1(x) := diff(N1(x),x)$
> dN2(x) := diff(N2(x),x)$
> dN3(x) := diff(N3(x),x)$
> Nij_quad: [N1(x),N2(x),N3(x)]$
> dNij_quad: map(lambda([X],diff(X,x,1)), Nij_quad)$
you'll have to be more explicit here.
when i enter these expressions, i get what appears to be
a meaningful result. what do you get?
what were you expecting?
hope this helps,
robert dodier