When you do it by hand, due to communitive property of vector matrix, the
equation
| ( Vi - Vj ) - ( Vj - Vk ) |
will become
| ( Vi + Vk ) |
since you multiply the -1 to the right side and add them.
and with using the Math.sqrt((Xi+Xk)^2+(Yi+Yk)^2)
will give you the amplitude of the vector.
---
Chris Kim
Iowa State University
>From: Tien Tran Thuong <[EMAIL PROTECTED]>
>Reply-To: Discussion list for Java 3D API <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: Re: [JAVA3D]
>Date: Tue, 6 Feb 2001 14:36:12 +0100
>
>thank you for you reply
>
>there are three point: i, j and k.
>Vi = (Xi, Yi), Vj = (Xj, Yj) and Vk = (Xk, Yk) are the coordinates of
>i,j,k
>I'd like to know how to calculate:
>| ( Vi - Vj ) - ( Vj - Vk ) |
>
>it's knew that : | Vi - Vj | = Math.sqrt( (Xi-Xj)*(Xi-Xj) -
>(Yi-Yj)*(Yi-Yj) )
>
>thank you
>
> > Hi Tien,
> >
> > Are you referring that "Vi-1" is "V sub i minus1" and "Vi+1" is "V sub i
> > plus 1"?
> >
> > | ( Vi-1 - Vi ) - ( Vi - Vi+1 ) |
> >
> > ----
> > Chris Kim
> > Iowa State University
> >
> > >From: Robert Pies <[EMAIL PROTECTED]>
> > >Reply-To: Discussion list for Java 3D API
><[EMAIL PROTECTED]>
> > >To: [EMAIL PROTECTED]
> > >Subject: Re: [JAVA3D]
> > >Date: Tue, 6 Feb 2001 13:30:19 +0100
> > >
> > >Hi Tien,
> > >
> > >I can't make sense out of your expression for at least 2 reasons:
> > >
> > >a) if Vi is a vector (xi,yi), the term 'Vi-1' doesn't make sense
> > >b) 'Vi-Vi' would be (0,0), so all the Vi's in your expression cancel
> > > out...
> > >
> > >Maybe the '-' in your expression is really a '*' denoting the
> > >(inner) vector-product?
> > >
> > >If you tell the mailinglist what you're trying to do, maybe some-
> > >one can make sense of it and help you.
> > >
> > >cheers,
> > >
> > >Robert.
> > >
> > >
> > >
> > > > Tien Tran Thuong wrote:
> > > >
> > > > Hello,
> > > >
> > > > Could anyone show me please how to calculate the expression below :
> > > >
> > > > | ( Vi-1 - Vi ) - ( Vi - Vi+1 ) |
> > > >
> > > > Where Vi = (xi,yi) is coordinate of the i-th vertex.
> > > >
> > > > Thank you in advance
> > >
> > >--
> > >
> > >---------------------------------------------------
> > >Robert Pies
> > >Ludwigstr. 58
> > >04315 Leipzig
> > >Germany
> > >+49-341-6888217 (phone&fax)
> > >[EMAIL PROTECTED]
> > >
> > >
> > >--
> > >
> > >---------------------------------------------------
> > >Robert Pies
> > >Ludwigstr. 58
> > >04315 Leipzig
> > >Germany
> > >+49-341-6888217 (phone&fax)
> > >[EMAIL PROTECTED]
> > >
> >
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