"Russell Towle" <rto### [at] inreachcom> wrote:
> "Leef_me" <nomail@nomail> wrote:
>
> > Hi Russell,
> >
> > Wrong time, yes. But you get to the same angle either way ya go.
> >
> > Try this code, it sure seems like the red and yellow cylinders are concentric.
>
>
> Nope, it's all wrong. They are concentric but for the wrong reasons. Note that
> the sunpos.inc macro requires its arguments to be {year, month, day, hours,
> minutes, ***central meridian of time zone***, latitude, longitude}. So, say you
> live at latitude -117.15 degrees. The time zone meridian you must use will be
> some multiple of fifteen degrees. Say, if you are eight hours behind Greenwich
> time, then 8*15=120; and -120 degrees will be your central meridian. Hence I
> change your example to
>
> SunPos(2007, 10, 18, 12, 2, -120, 32.71, -117.15),
>
> but this would be incorrect if you are in the Mountain zone, rather than the
> Pacific
> zone.
>
> This will show the differing orientation of the cylinders:
>

Hi Russell,

Yeah, you're right. I copy/pasted that example, from where I don't recall.
The lat/long is of a location in Oklahoma, it's no where near Greenwich,
well it is the same planet ;)  So the meridian is wrong. I ran my example
again and the Messages window has this:

REMARK:
Longitude differs by more than 30 degrees from timezone meridian.
Local timezone meridian is:   -8
Longitude is: -117

My particular example seems to not show the particular problem with the
'rotate' function.  I should have tried a few more examples.

Sorry about my error.

Leef_me

Post a reply to this message