Apparent & absolute magnitude

I have made a simple program that calculates the absolute magnitude when you
give the distance and apparent magnitude. it can also calculate apparent
magnitude and distance. You can download it at
http://users.pandora.be/alex.duerloo/MAGNIT.EXE (41 Kb) If you want the
code, here it is, it's written in QBasic 4.5:

DECLARE FUNCTION LOGAR10! (X!)

10 DO
CLS
PRINT "Magnitude calculator by Alexander Duerloo (2003)"
PRINT ""
PRINT ""
PRINT "What do you want to calculate?"
PRINT ""
PRINT "1. The absolute magnitude of a star"
PRINT "2. The apparent magnitude of a star"
PRINT "3. The distance of a star"
PRINT "4. Exit"
PRINT ""
ch$ = INPUT$(1)
ch = INT(VAL(ch$))
IF ch 0 AND ch 5 THEN
EXIT DO
END IF
BEEP
LOOP
CLS
SELECT CASE ch
CASE 1
INPUT "What's the apparent magnitude of the star"; apmag
INPUT "What's the distance of the star (in light-years)"; dist
dist = dist / 3.26
abmag = apmag - ((-5) + (5 * LOGAR10(dist)))
PRINT ""
PRINT "The absolute magnitude of the star is "; abmag; "."
PRINT ""
SHELL "pause"
CASE 2
INPUT "What's the absolute magnitude of the star"; abmag
INPUT "What's the distance of the star (in light-years)"; dist
dist = dist / 3.26
apmag = abmag + ((-5) + (5 * LOGAR10(dist)))
PRINT ""
PRINT "The apparent magnitude of the star is "; apmag; "."
PRINT ""
SHELL "pause"
CASE 3
INPUT "What's the apparent magnitude of the star"; apmag
INPUT "What's the absolute magnitude of the star"; abmag
dist = 10 ^ (.2 * (apmag - abmag + 5))
PRINT ""
PRINT "The distance of the star is "; dist * 3.26; "light-years."
PRINT ""
SHELL "pause"

CASE 4
SYSTEM
END SELECT
GOTO 10



FUNCTION LOGAR10 (X) STATIC
LOGAR10 = LOG(X) / LOG(10#)
END FUNCTION

maybe you should move on to another newsgroup where you can fully express
your psychological problems, cypherpunk that would make us all happy

schreef in bericht
...
Alexander Duerloo wrote:
I have made a simple program that calculates the absolute magnitude
when you
give the distance and apparent magnitude. it can also calculate
apparent
magnitude and distance. You can download it at
http://users.pandora.be/alex.duerloo/MAGNIT.EXE (41 Kb) If you want
the
code, here it is, it's written in QBasic 4.5:

BEEP

Heh - kids.

"Alexander Duerloo" wrote in message
...
by the way, what do you mean with low-quality code

schreef in bericht
...
Alexander Duerloo wrote:
maybe you should move on to another newsgroup where you can fully
express
your psychological problems, cypherpunk that would make us all happy

And maybe you should not post such poor quality
source code to the Internet, if you want to
avoid ridicule.

Don't let the flamers get you down, Alexander. At
least you contributed some technical content. We
could do with more of it, and at all levels of
expertise.

If you enjoy tinkering with BASIC code in an
astronomy vein, I invite you to take a look at
the contents of The Orrery newsletter:

http://members.attcanada.ca/~gneill/

In message ,
writes
Alexander Duerloo wrote:
I don't think comments change the way the program runs,

WHOOSH!!!

As in "whoosh, straight over my head"? Why don't _you_ try contributing
something?
--
"Roads in space for rockets to travel....four-dimensional roads, curving with
relativity"
Mail to jsilverlight AT merseia.fsnet.co.uk is welcome.
Or visit Jonathan's Space Site http://www.merseia.fsnet.co.uk

look, cypherpunk: if insulting other people at an astronomy newsgroup makes
you feel cool, then do it. I don't care because most of the people in this
newsgroup ignore you and your posts becaus the are ridiculous, antisocial
and insulting messages
schreef in bericht
...
wrote:
wrote:
Alexander Duerloo wrote:
by the way, what do you mean with low-quality code

No matter how trivial you feel it is to read the source code,
you should have COMMENTS documenting the program flow and
algorithms.

It's the difference between amateur and professional.

Reason: 85% of the cost of source code is in the maintenance.

That's partly true (although a lot of "professional" code I've worked
with has been very poorly documented) but Alexander wasn't posting
this as an all-singing-all-dancing professional package, just as
something of interest for the astronomical community.

At least it's on topic and useful, which is a pleasant change from a
lot of recent postings....

Yeah, he was trying to be helpful. It's just a shame to see
him using bad habits which will be hard to shake later.

I seem to recall there were "magic" numbers in
his code too. (unexplained constants) If he's
going to donate code to people to learn from,
it would be good form to take a few extra
minutes to comment it up.

Nothing wrong with BASIC, BTW.

On Sat, 12 Jul 2003 12:43:34 +0100, Alexander Duerloo wrote:

I have made a simple program that calculates the absolute magnitude when
you give the distance and apparent magnitude. it can also calculate
apparent magnitude and distance. You can download it at
http://users.pandora.be/alex.duerloo/MAGNIT.EXE (41 Kb) If you want the
code, here it is, it's written in QBasic 4.5:

Thanks Alexander. It is a nice little program. I am sure I shall use it.
Its a long time since such a little gem appeared in this ng.

--

Gautam Majumdar

Here are the formulas used in the program:

M=Absolute magnitude
m=Apparent Magnitude
d=Distance (parsec)

M = m - ((-5) + 5 log d)
m = M + ((-5) + 5 log d)
d = 10 ^ (0.2 (m - M + 5))

If you are smarter than you seem to be you could now easily reconstruct the
program

In article ,
wrote:

It's been years since I stopped doing math and switched to
using the computer (lots of numbers, but for abstracts),
but I think I remember e: 2.71828184590452356...

....except that it should read: 2.71828182845904523536028747135...
....so you skipped a "28" sequence there..... and your last digit
shouldn't be 6..... :-)

Personally I remember it this far: 2.718281828

The repetition of "1828" is what I remember most easily.

--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://www.stjarnhimlen.se/
http://home.tiscali.se/pausch/

Paul Schlyter wrote:

In article ,
wrote:

It's been years since I stopped doing math and switched to
using the computer (lots of numbers, but for abstracts),
but I think I remember e: 2.71828184590452356...

...except that it should read: 2.71828182845904523536028747135...
...so you skipped a "28" sequence there..... and your last digit
shouldn't be 6..... :-)

Personally I remember it this far: 2.718281828

The repetition of "1828" is what I remember most easily.

The "459" isn't hard either.
1828 = the year after Beethoven died
4, 5, 9 = his three most widely known symphonies

At least that's how my applied math teacher explained it, and it must
work, because almost 30 years later I still remember it. :-)

-- Bill

no problem