What does a comma mean in a trig formula?

Hi,

I'm trying to use an equation an astronomy website (eq. 23), but it contains a comma and I'm not sure why / what it means! The equation is:

Code:

`A = arctan(sin H, cos H sin φ − tan δ cos φ)`

I know the values of H, φ and δ, but I don't know what to do about the comma. Their working, given using the values previously worked out, is:

Code:

`A = arctan(sin(3.7838°), cos(3.7838°) * sin(52°) − tan(4.7585°) * cos(52°))`

= 5.1302°

Obviously that still includes the comma, with no clue to it's meaning! Any suggestions whatsoever would be very much appreciated! (Happy)

EDIT: I've put this in the High School forum as the actual trig isn't that difficult - I have no idea how difficult the comma is, so didn't really know where else to post it anyway! Hope that's OK.