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Global operators

It is important to understand the difference between a global operator such as dx() and a local operator such as sin() .

To compute dx(f) at vertex q we need f at all neighbors of q. Therefore evaluation of dx(2*f) require the computation of 2*f at all neighbor vertices of q before applying dx() ; but in which memory would the result be stored? Therefore Gfem does not allow this and forces the user to declare a function g =2*f before evaluation of dx(g) ; Hence in

g = 2*f;
h = dx(g) * dy(f);

the equal sign forces the evaluation of g at all vertices, then when the second equal signs forces the evaluation of the expression on the right of h at all vertices , everything is ready for it.

Global operators are

dx(), dy(), convect(), intt[], int()[]

Example of forbidden expressions:

intt[f+g], dx(dy(g)), dx(sin(f)), convect(2*u...)



2001-11-04