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atan in IRAF

Michael Mommert wrote on Apr 24, 2009

Hi everybody,

I have to calculate polarization angles and therefore I need the atan function. Unfortunately, I cannot access this function and IRAF always wants me to use atan2, which is actually not the same.

Example:

cl> print (atan(0.3))
ERROR: `atan2' expects two arguments


What am I doing wrong?
Thanks for any help,

Michael

Michael Mommert wrote on Apr 24, 2009

problem solved:

atan(x) = atan2(x,1.0)

right?

Mike Fitzpatrick wrote on Apr 24, 2009

Right. I think the logic behind not supplying an 'atan' function was that the CL allows abbreviation and there might be some ambiguity between atan/atan2.

-Mike

Last post on Apr 24, 2009