Re: Multiply some colums, discarding others

[Norm Hecht]

Try B = [A(:,1) A(:,2).*A(:,3)]

Norm Hecht
Thornton, CO, USA

On Nov 24, 2009, at 12:29 PM, Renato S. Yamane wrote:

> Hi,
> 
> I have a doubt about how can I use Octave :-)
> 
> E.g.:
> 
> Matrix A is "freq", "impedance" and "phase", like this:
> 
> A =
>       20.66      12.32      49.63
>       21.47      13.75      48.86
>       22.30      15.92      47.71
>       23.17      18.43      45.06
>       24.07      22.61      39.76
> 
> I would like to get another Matrix, B, with the result of multiplication 
> of "impedance" and "phase", like this:
> 
>       A(1,2) * cos(A(1,3))
>       A(2,2) * cos(A(2,3))
>       A(3,2) * cos(A(3,3))
>       A(4,2) * cos(A(4,3))
>       A(5,2) * cos(A(5,3))
> 
> As you can see, the collum "frequency" is not used.
> 
> The problem is: Matrix "A" have a lot of lines and I need avoid type one 
> by one, so I would like to know if is possible multiply *automatically* 
> to get "frequency" and multiplication of impedance and phase, like this:
> 
> Matrix "B" =
> 
>       20.66      A(1,2) * cos(A(1,3))
>       21.47      A(2,2) * cos(A(2,3))
>       22.30      A(3,2) * cos(A(3,3))
>       23.17      A(4,2) * cos(A(4,3))
>       24.07      A(5,2) * cos(A(5,3))
> 
> Regards,
> Renato S. Yamane
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