Eph1 = 0.720  # actual photon energy in keV. Don't forget .0 at the end!!
Eph2 = 0.710  # desired photon energy in keV. Don't forget .0 at the end!!

do_elog = False

undlist = ("SATUN06","SATUN07","SATUN08","SATUN09","SATUN10","SATUN11","SATUN12","SATUN13",
           "SATUN15","SATUN16","SATUN17","SATUN18","SATUN19","SATUN20","SATUN21","SATUN22")

K1, K2 = {}, {}
for und in undlist:
  K = caget(und + "-UIND030:K_SET")
  K1[und] = K
  K2[und] = ((Eph1 / Eph2 * (K**2 + 2) - 2))**0.5
print K1,K2
for und in undlist: caput(und + "-UIND030:K_SET",  K2[und])

#Elog entry
if do_elog:
  title = "Wavelength change"
  log_msg =           "Old photon energy:  %0.2f"   % Eph1            + " kev\n"
  log_msg = log_msg + "New photon energy:  %0.2f"   % Eph2            + " keV\n"
  elog(title, log_msg)

set_return("Success")