#
# evolve:
#
# The "evolve" procedure is the time-step loop for a scheme.
#

printf("evolve procedures:  \
evolve, \
get_animation, \
get_3d_plot\n");

evolve := proc(u, g, scheme, t_min, t_max, plot_freq)
  local t, data, n, dt, stencil, l_bc, r_bc, max_time_step;
  
  stencil, l_bc, r_bc, max_time_step := op(scheme);
  t := t_min;
  data := get_profile_of_field_at_time(u, g, t_min);
  for n from 1 while t < t_max do
    dt := max_time_step(u, g):
    advance_field(u, g, stencil, l_bc, r_bc, dt);
    t := t + dt;
    if (modp(n, plot_freq) = 0) then
      data := data, get_profile_of_field_at_time(u, g, t);
    fi
  od;
  [data]
end:

get_animation := proc(data)
  local pick, data2d;

  pick := x -> map(y -> [op(1,y), op(3,y)], x);
  data2d := map(pick, data);
  PLOT(ANIMATE(op(map(x->[x], map(CURVES, data2d, COLOUR(RGB,0,0,1))))),
    AXESLABELS(x, u))
end:

get_3d_plot := proc(data)

  PLOT3D(MESH(data), STYLE(PATCHCONTOUR))
end: