Maya Camera to RenderMan - part2

for maya python script
if float(dspyFormatX) > float(dspyFormatY):
frameWidth = cmds.getAttr('%s.hfa' % camName)
else:
frameWidth = cmds.getAttr('%s.vfa' % camName)
fov = math.degrees(2 * math.atan(frameWidth * 12.7 / focalLength))