function plan = plate_fd_plan(params)
% PLATE_FD_PLAN  Grid, time step, cost and statics of the explicit scheme, before a run.
%
%   plan = plate_fd_plan(params) assembles the model (plate_model) and reports
%     plan.nx, plan.ny, plan.dx, plan.dy    grid (nodes include the edges of the box)
%     plan.dt_max                          largest stable time step [s]
%     plan.dt                              step actually used, params.fd.cfl * dt_max
%     plan.nsteps, plan.ncells, plan.cell_steps   problem size (ncells counts every grid node)
%     plan.nunknowns                       nodes the scheme actually updates
%     plan.rigid_hz                        frequencies of the rigid-body modes the
%                                          mount leaves (sway, swing, spin or heave and
%                                          tilts), NaN for an unstable one
%     plan.rigid_names                     the rigid-body coordinates of the mount
%     plan.rigid_mode_names                the coordinate that dominates each mode
%     plan.sag                             largest static deflection under gravity [m]
%     plan.gx, plan.gy, plan.gz            direction of gravity in plate coordinates
%     plan.mass, plan.xc, plan.yc          plate mass and centre of mass
%     plan.tension                         thread tensions [N] (empty otherwise)
%     plan.notes                           remarks about the mount and the statics
%
%   Because the step scales with dx^2, halving the grid spacing costs eight
%   times as many cell updates for the same simulated time; and because the
%   pendulum motion of a hanging plate takes a second or so to show while the
%   step is a few microseconds, a run is hundreds of thousands of steps.

mdl = plate_model(params);
plan.nx = mdl.nx; plan.ny = mdl.ny; plan.dx = mdl.dx; plan.dy = mdl.dy;
plan.dt_max = mdl.dt_max;
plan.dt = mdl.dt;
plan.nsteps = mdl.nsteps;
plan.ncells = mdl.ncells;
plan.nunknowns = mdl.nunknowns;
plan.cell_steps = plan.ncells * plan.nsteps;
plan.rigid_hz = mdl.rigid_hz(:)';
plan.rigid_names = mdl.mnt.rigid_names;
plan.rigid_mode_names = mdl.rigid_mode_names;
plan.sag = mdl.st.sag;
plan.gx = mdl.mnt.gx; plan.gy = mdl.mnt.gy; plan.gz = mdl.mnt.gz;
plan.mass = mdl.mnt.mass; plan.xc = mdl.mnt.xc; plan.yc = mdl.mnt.yc;
plan.tension = zeros(1, 0);
if mdl.ps.solved && any(strcmp(mdl.mnt.type, {'thread', 'threads'}))
    plan.tension = mdl.ps.up(mdl.ps.fixed_nodes)';
end
plan.Om2 = mdl.Om2;
plan.notes = mdl.notes;
end