Search for Convolution method in JAVA

Hello!

I'm searching for a method/class/package in JAVA that implements a linear
convolution algorithm between two signals. For example 
"public convolution(double[] signal1, double[] signal2)" that convolves
signal 1 with 2. I've searched in many webpages, but I've found nothing. 

I think, I'm serching for any easy method, but I don't know why I can't
find it. Somebody can help me? 

Me e-mail is: fositin@hotmail.com

I'm sorry if my english isn't perfect. 

Walker wrote:

> Hello!
>
> I'm searching for a method/class/package in JAVA that implements a linear
> convolution algorithm between two signals. For example
> "public convolution(double[] signal1, double[] signal2)" that convolves
> signal 1 with 2. I've searched in many webpages, but I've found nothing.
>
> I think, I'm serching for any easy method, but I don't know why I can't
> find it. Somebody can help me?

Convolution is easy to code yourself. If s1 and s2 are two causal
signals (ie. s1(n) = 0 for n < 0), then the convolution y = s1 * s2 can
be calculated as

y(n) = sum_k^n s1(k) s2(n-k)

If the lengths L1 of s1 and L2 of s2 are finite, then the length of y
is equal to L1 + L2 - 1.

Regards,
Andor

>Convolution is easy to code yourself. If s1 and s2 are two causal
>signals (ie. s1(n) = 0 for n < 0), then the convolution y = s1 * s2 can
>be calculated as
>
>y(n) = sum_k^n s1(k) s2(n-k)
>
>If the lengths L1 of s1 and L2 of s2 are finite, then the length of y
>is equal to L1 + L2 - 1.
>
>Regards,
>Andor
>
>

Thank you, 
I know it, but it would be easyer when somebody would have this
class/method. I can programm it, but: what happens when the signals aren't
causals?

Thanks

Walker wrote:

> >Convolution is easy to code yourself. If s1 and s2 are two causal
> >signals (ie. s1(n) = 0 for n < 0), then the convolution y = s1 * s2 can
> >be calculated as
> >
> >y(n) = sum_k^n s1(k) s2(n-k)
> >
> >If the lengths L1 of s1 and L2 of s2 are finite, then the length of y
> >is equal to L1 + L2 - 1.
> >
> >Regards,
> >Andor
> >
> >
>
> Thank you,
> I know it, but it would be easyer when somebody would have this
> class/method. I can programm it, but: what happens when the signals aren't
> causals?

In that case the sum either comes from or goes to infinity (or both)
... not something you want to calculate with Java :-). Usually, either
s1 and s2 or at least one of them can be considered finite in duration.
In that case, each entry in y(n) can be computed using a finite sum.

"Walker" <fositin@hotmail.com> wrote in message 
news:BOOdneDcHYbg6srZnZ2dnUVZ_uWdnZ2d@giganews.com...
> >Convolution is easy to code yourself. If s1 and s2 are two causal
>>signals (ie. s1(n) = 0 for n < 0), then the convolution y = s1 * s2 can
>>be calculated as
>>
>>y(n) = sum_k^n s1(k) s2(n-k)
>>
>>If the lengths L1 of s1 and L2 of s2 are finite, then the length of y
>>is equal to L1 + L2 - 1.
>>
>>Regards,
>>Andor
>>
>>
>
> Thank you,
> I know it, but it would be easyer when somebody would have this
> class/method. I can programm it, but: what happens when the signals aren't
> causals?

Actually the formulation above doesn't rely on either sequence representing 
anything "causal".
You get to define the indices relative to time.

Fred