Wed Feb 17 21:50:26 EST 2016

Summary: why spice looks like it does

- KCL gives an easy way to dervice equations from a netlist: one
  equation per node, except ground node.

- This expresses connectivity as an admittance (conductance) matrix G,
  each element corresponding to the conductance of a single resistor.

- To deal with ideal voltage sources, the equations can be re-arranged
  from Gv=i, [G|-1][v|i]^T=0 form to Ap+Bs=0, where p contains all
  variabiable voltages/currents and s contains all voltage/current

- If G represents the connectivity of the network, each element in G,
  if not a static resistor, is a current linear approximation of
  dynamic and nonlinear effects.  Offsets are determined by voltage,
  current sources.