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From: Snow White on 29 Apr 2010 06:22
Hello,

I have two vectors v1 and v2 and i want to take their dot product(inner product) as i want to eliminate calculation of an angle but the problem is that the vectors are not of equal length. v1 is 1x19 and v2 is 1x3. Is there a way to modify these and get a dot product?

Bye
From: Torsten Hennig on 29 Apr 2010 02:43
> Hello,
>
> I have two vectors v1 and v2 and i want to take their
> dot product(inner product) as i want to eliminate
> calculation of an angle but the problem is that the
> vectors are not of equal length. v1 is 1x19 and v2 is
> 1x3. Is there a way to modify these and get a dot
> product?
>
> Bye

If you are only interested in the angle betweeen
the second vector and the first vector projected
from IR^19 to IR^3, you can calculate
v1(1)*v2(1)+v1(2)*v2(2)+v1(3)*v2(3)
as their inner product.
In general, an angle between vectors of different
dimensions is ambiguous and thus not well-defined.

Best wishes
Torsten.
From: Snow White on 29 Apr 2010 07:05
I cant do that actually v1 is a vector of angle and v2 is another vector that has to be multiplied with the angles

Torsten Hennig <Torsten.Hennig(a)umsicht.fhg.de> wrote in message <741854198.42087.1272537831432.JavaMail.root(a)gallium.mathforum.org>...
> > Hello,
> >
> > I have two vectors v1 and v2 and i want to take their
> > dot product(inner product) as i want to eliminate
> > calculation of an angle but the problem is that the
> > vectors are not of equal length. v1 is 1x19 and v2 is
> > 1x3. Is there a way to modify these and get a dot
> > product?
> >
> > Bye
>
> If you are only interested in the angle betweeen
> the second vector and the first vector projected
> from IR^19 to IR^3, you can calculate
> v1(1)*v2(1)+v1(2)*v2(2)+v1(3)*v2(3)
> as their inner product.
> In general, an angle between vectors of different
> dimensions is ambiguous and thus not well-defined.
>
> Best wishes
> Torsten.
From: John D'Errico on 29 Apr 2010 07:34
"Snow White" <gulesaman(a)gmail.com> wrote in message <hrbmkc$qor$1(a)fred.mathworks.com>...
> Hello,
>
> I have two vectors v1 and v2 and i want to take their dot product(inner product) as i want to eliminate calculation of an angle but the problem is that the vectors are not of equal length. v1 is 1x19 and v2 is 1x3. Is there a way to modify these and get a dot product?
>

You are not listening. What you have asked to do is
mathematically nonsensical.

A dot product is a well defined thing, but not between
things of different dimensions. So please explain what
these vectors represent, and what the angle is that you
wish to compute in that context, and we may be able
to help you.

John
From: Snow White on 29 Apr 2010 09:18
Exactly! i knw a dot product is between vectors of the same length. i wanted to know is there a possibility of rearranging them such that this might be possible?

"John D'Errico" <woodchips(a)rochester.rr.com> wrote in message <hrbqrb$5s$1(a)fred.mathworks.com>...
> "Snow White" <gulesaman(a)gmail.com> wrote in message <hrbmkc$qor$1(a)fred.mathworks.com>...
> > Hello,
> >
> > I have two vectors v1 and v2 and i want to take their dot product(inner product) as i want to eliminate calculation of an angle but the problem is that the vectors are not of equal length. v1 is 1x19 and v2 is 1x3. Is there a way to modify these and get a dot product?
> >
>
> You are not listening. What you have asked to do is
> mathematically nonsensical.
>
> A dot product is a well defined thing, but not between
> things of different dimensions. So please explain what
> these vectors represent, and what the angle is that you
> wish to compute in that context, and we may be able
> to help you.
>
> John
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