get DC power flow matrix in IEEE 14 bus system from matpower

[Song Tan]

Hello All,
  I am new to matpower and was wondering whether someone can give me some
sample codes to get the DC power flow matrix of IEEE 14 system.

  Specifically, what parameters I should pass to function makeBdc or
makePTDF?  And how should I get those parameters from the
loadcase('case14')?

  I really appreciate any hints, thanks!

Best,
                 Song Tan