test(2) symbolic arguments in variational expressions

Other Alias

trial

DESCRIPTION

These classes are used for test and trial functions involved in variational formulations. Variational formulations could be specified by expressions, in the spirit of c++ embeded languages. A variable of the test type represents the formal argument (the test-function) in the definition of a linear form, as in:

    geo omega ("circle");
    space Xh (omega, "P1");
    test v(Xh);
    field lh = integrate (omega, 2*v);

For a bilinear form, the test-function represents its second formal argument, while the first one is designed by the trial type:

    trial u(Xh);
    test  v(Xh);
    form m = integrate (omega, u*v),
         a = integrate (omega, dot(grad(u),grad(v)));

The field_vf class is abble to represents either test or trial types: it could be used to formaly define a differential operator, as:

    D(u) = (grad(u)+trans(grad(u)))