function body = bass_body(P)
% BASS_BODY The parameterized modal body seen at the bridge.
%
% This is the empirical part of the model: the corpus of a double bass is
% not solved from plates and ribs here, it is a table of measured-plausible
% resonances, each reduced to what the string and the listener can see of
% it. Per mode: the frequency, the Q, the effective mass at the bridge foot
% (which sets the admittance the string is loaded by), the radiating area
% (the net volume the body displaces per unit bridge displacement in that
% mode), and whether it radiates as a monopole or a dipole. The first row
% is A0, the f-hole Helmholtz resonance: the one mode that moves net volume
% through the f-holes and therefore the one monopole; every corpus mode
% above it displaces the top plate against the surrounding air with no net
% flow and radiates as a dipole across the body. The table follows the
% published admittance and radiativity measurements of orchestral basses in
% shape (A0 near 60 Hz, the main wood resonances between 90 and 250 Hz, a
% falling effective area above), with the absolute levels set by the trims
% in bass_defaults.m. Modes above the table are NOT ignored: their
% collective resistive load enters as residual_y in bass_basis.m and their
% radiation as the direct term in bass_radiate.m.
%
% Mass-normalized amplitude at the bridge: a_j = sqrt(bridge_mobility/m_j),
% so bridge_mobility scales the whole admittance without retuning the table.

fb = [60.0 97.0 113.0 135.0 167.0 205.0 252.0 310.0 382.0 470.0 578.0 711.0];
Qb = [28.0 30.0 30.0 30.0 28.0 26.0 24.0 22.0 20.0 19.0 18.0 17.0];
mb = [1.6 1.2 1.1 1.0 0.95 0.90 0.90 1.0 1.1 1.3 1.5 1.8];          % kg at the bridge
Sb = [0.055 0.055 0.048 0.032 0.022 0.015 0.010 0.0075 0.0055 0.004 0.003 0.0022]; % m^2
mono = [1 0 0 0 0 0 0 0 0 0 0 0];

nb = length(fb);
f = reshape(fb, nb, 1);
f(1) = P.a0_hz;
f(2:nb) = f(2:nb) * P.body_trim;

body.n = nb;
body.f = f;
body.omega = 2 * pi * f;
body.zeta = reshape(0.5 ./ (Qb * P.body_q_scale), nb, 1);
body.a = reshape(sqrt(P.bridge_mobility ./ mb), nb, 1);   % 1/sqrt(kg)
body.S = reshape(Sb * P.rad_area_scale, nb, 1);           % m^2
body.mono = reshape(mono, nb, 1);
end