SLA_EPCO - Convert Epoch to B or J

ACTION:

Convert an epoch to Besselian or Julian to match another one.

CALL:

D = sla_EPCO (K0, K, E)

GIVEN:

K0	C	form of result: `B'=Besselian, `J'=Julian
K	C	form of given epoch: `B' or `J'
E	D	epoch

RETURNED:

sla_EPCO

D

the given epoch converted as necessary

NOTES:

1. The result is always either equal to or very close to the given epoch E. The routine is required only in applications where punctilious treatment of heterogeneous mixtures of star positions is necessary.
2. K0 and K are not validated. They are interpreted as follows:
   • If K0 and K are the same, the result is E.
   • If K0 is `B' and K isn't, the conversion is J to B.
   • In all other cases, the conversion is B to J.