mixed.c

Boundary functions do not understand u.n, u.t yet. A workaround for this example is to replace u.t with *_s* in the RHS.

vector u[];
double bi = 2.;

u.t[bottom] = u.t[]*(2. - bi*Delta)/(2. + bi*Delta);
u.t[bottom] = val(_s,0)*(2. - bi*Delta)/(2. + bi*Delta); // this is the workaround

int main() {}