imlintran
raa wrote on Feb 14, 2006
Hi,
I am new to IRAF. I have to deproject a disc galaxy. From literature it seems that the task "imlintran" is capable of doing it. Now the help file gives that the transformation is:
xt = xt * cos (xrotation) - yt * sin (yrotation)
yt = xt * sin (yrotation) + yt * cos (yrotation)
where xrotation, yrotation should be in degrees. The problem I am facing is with regard to cos(yrotation). Is it correct? should it be cos(xrotation) as the usual rotation matrix?
Raa
I am new to IRAF. I have to deproject a disc galaxy. From literature it seems that the task "imlintran" is capable of doing it. Now the help file gives that the transformation is:
xt = xt * cos (xrotation) - yt * sin (yrotation)
yt = xt * sin (yrotation) + yt * cos (yrotation)
where xrotation, yrotation should be in degrees. The problem I am facing is with regard to cos(yrotation). Is it correct? should it be cos(xrotation) as the usual rotation matrix?
Raa
Mike Fitzpatrick wrote on Feb 14, 2006
The help page is correct, at least in the sense that the code is implemented that way. I can't explain the difference off the top of my head, but keep in mind there are separate angles specified for the X and Y rotation where the standard rotation matrix assumes orthogonal axes and only one rotation angle. Perhaps you can dig up the derivation that arrives at the cos(yrot) term, I couldn't find it in the online docs.
-Mike
-Mike
Last post on Feb 14, 2006