next up previous contents index
Next: Pde() Up: Solving an equation Previous: Solving an equation   Contents   Index

Onbdy()

Its purpose is to define a boundary condition for a Partial Differential Equation (PDE).

The general syntax is

onbdy(ib1, ib2,...) id(u)+<expression>*dnu(u) = g
onbdy(ib1, ib2,...) u = g
where ib's are boundary identification numbers, <expression> is a generic expression and g a generic function.

The term id(u) may be absent as in -dnu(u)=g . dnu(u) represents the conormal of the PDE, i.e.

$\displaystyle \pm\vec\nabla u . n $

when the PDE operator is

$\displaystyle a * u - \vec\nabla.(\pm\vec\nabla u)$



Debian/ARM Build Daemon #4 2001-12-12