Particle indicies

Packing files will have vecPosX and vecPoxY and are of size [N x 1] where N is the number of particles after cleanRats(). They are not sorted in any particular order.

To get the position of particle j, simple access

j = 2;
vecPosX(j)
vecPosY(j)

Additional variables with options.hertzian = true

When pack() is run with options.hertzian = true, the output .mat file contains three additional variables describing the linearized contact network at the jammed state.

So there be the particle index j and now a contact index k.

Addiitonal variables

Example

data = load('2D_N400_P0.0001_Width20_Seed1.mat');

k  = 1;                        % pick contact k
ii = data.vecHertzNN(k);       % index of particle i
jj = data.vecHertzMM(k);       % index of particle j

x_i  = data.vecPosX(ii);       % position of particle i
x_j  = data.vecPosX(jj);       % position of particle j
d_i  = data.vecDiameter(ii);   % diameter of particle i
keff = data.vecHertzKeff(k);   % stiffness of this contact

Notes

• vecHertzNN(k) < vecHertzMM(k) always — each pair is stored once
• Indices refer to the post-cleanRats particle list — they index directly into vecPosX, vecPosY, vecDiameter (and vecPosZ for 3D)