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From: ravi on 19 Feb 2010 21:46
I have 2 matrices.

A =

658 96 1
760 292 1
777 353 1

B =

1072 103 1
1089 298 1
1034 357 1

Using the cross function how can I cross multiple each row one at a time? I know I have to use a for loop. I've been trying but just dont know how.

Can anyone help.
Best
ravi
From: Matthew on 19 Feb 2010 22:35
You don't need a loop. Just use the third argument in cross, i.e.

cross(A,B,1)

"ravi " <ravi_071(a)hotmail.com> wrote in message <hlnidb$9u1$1(a)fred.mathworks.com>...
> I have 2 matrices.
>
> A =
>
> 658 96 1
> 760 292 1
> 777 353 1
>
> B =
>
> 1072 103 1
> 1089 298 1
> 1034 357 1
>
> Using the cross function how can I cross multiple each row one at a time? I know I have to use a for loop. I've been trying but just dont know how.
>
> Can anyone help.
> Best
> ravi
From: ravi on 19 Feb 2010 23:00
I don't think that will work matthew.

I tried it ,i.e. cross(A,B,1) and got the same result.

i am looking to cross multiply each row of A by each row of B.

So for example.

cross(A(1,:), B(1,:)) will give me :

>> cross(A(1,:), B(1,:))

ans =

-7 414 -35138


I now want to do this for all the following rows of A and B. That's why I thought a for loop was needed.

Any other suggestion?

Thanks
ravi
From: ravi on 19 Feb 2010 23:04
I don't think that will work matthew.

I tried it ,i.e. cross(A,B,1) and got the same result.

i am looking to cross multiply each row of A by each row of B.

So for example.

cross(A(1,:), B(1,:)) will give me :

>> cross(A(1,:), B(1,:))

ans =

-7 414 -35138


I now want to do this for all the following rows of A and B. That's why I thought a for loop was needed.

Any other suggestion?

Thanks
ravi
From: Wayne King on 19 Feb 2010 23:31
"ravi " <ravi_071(a)hotmail.com> wrote in message <hlnmvj$ghf$1(a)fred.mathworks.com>...
> I don't think that will work matthew.
>
> I tried it ,i.e. cross(A,B,1) and got the same result.
>
> i am looking to cross multiply each row of A by each row of B.
>
> So for example.
>
> cross(A(1,:), B(1,:)) will give me :
>
> >> cross(A(1,:), B(1,:))
>
> ans =
>
> -7 414 -35138
>
>
> I now want to do this for all the following rows of A and B. That's why I thought a for loop was needed.
>
> Any other suggestion?
>
> Thanks
> ravi

Hi Ravi,

For the way you have your matrices,
cross(A',B')

the columns of the answer are the cross products of the rows of A and B.

Hope that helps,
Wayne
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