nonlinearpoisson.form

来自「Dolfin provide a high-performance linear」· FORM 代码 · 共 24 行

# Copyright (C) 2005 Garth N. Wells.
# Licensed under the GNU LGPL Version 2.1.
#
# First added:  2005
# Last changed: 2006-03-28
#
# The linearised bilinear form a(u,v) and linear form L(v) for
# the nonlinear equation - div (1+u) grad u = f
#
# Compile this form with FFC: ffc NonlinearPoisson.form.

element = FiniteElement("Lagrange", "triangle", 1)

v = TestFunction(element)
u = TrialFunction(element)
u0= Function(element)
f = Function(element)

#a = v.dx(i)*(1+u0*u0)*u.dx(i)*dx + v.dx(i)*2*u0*u*u0.dx(i)*dx
#L = v*f*dx - v.dx(i)*(1+u0*u0)*u0.dx(i)*dx
a = (1+u0*u0)*dot(grad(v), grad(u))*dx + 2*u0*u*dot(grad(v), grad(u0))*dx 
L = v*f*dx - (1+u0*u0)*dot(grad(v), grad(u0))*dx