scatter_meta(S{3}, 'j', 1, 'j', 2) will draw a scatter plot
where each point corresponds to a scattering path, the x axis
corresponds to j1, the y axis corresponds to j2
function scatter_meta(meta, field_name_1, id1, field_name_2, id2)
vec2plot = vec2plot(id1,:);
vec2plot2 = vec2plot2(id2,:);