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Re: Center of mass??? [message #17692]

Tue, 09 November 1999 00:00

Jonathan Joseph
Messages: 69
Registered: September 1998

Member

Well, I'm not going to take up JD's challenge,
but are you all sure you are answering the right
question?

I mean sure, great, if you happen to have
an MxNx.... array of masses then you've got
everything you need. But when I first read
Anders' post, I thought, "gee that sounds simple."

I thought of N masses at N locations,

m = 1D array of N masses
pos = D x N array of locations of the masses in D dimensions

then:

s=size(pos, /dimensions)
mm = m ## replicate(1,s(0))
cm = total(pos * mm, 2) / total(m)

Please someone correct me if I'm wrong.
Also, Is there a better way of multiplying
an MxN array by a one dimensional array of
length N such that each row of the MxN array
is multiplied by the corresponding element
of the one dimensional array?

-Jonathan

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[Message index]

		Re: Center of mass??? By: Jonathan Joseph on Tue, 09 November 1999 00:00
		Re: Center of mass??? By: J.D. Smith on Tue, 09 November 1999 00:00
		Re: Center of mass??? By: Dick Jackson on Tue, 09 November 1999 00:00
		Re: Center of mass??? By: davidf on Mon, 08 November 1999 00:00
		Re: Center of mass??? By: Paul Hick on Mon, 08 November 1999 00:00
		Re: Center of mass??? By: davidf on Thu, 11 November 1999 00:00
		Re: Center of mass??? By: Anders Wennerberg on Thu, 11 November 1999 00:00
		Re: Center of mass??? By: J.D. Smith on Wed, 10 November 1999 00:00
		Re: Center of mass??? By: davidf on Mon, 08 November 1999 00:00

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