How to use scilab's wfir filter?

[maxpla...@gmail.com]

I've tried using wfir, and i know how to set it to lowpass mode and to
set
its cutoff frequency and slope. However, once I set these values, how
do i apply the filter to a signal?

Do I simply multiply wfir by the signal in order to apply
this filter to the signal? I've tried doing this, but Scilab tells me
"Undefined operation for the given operands".

Sorry for my noobishness, but can someone please tell me how to
actually apply this filter to a
signal in scilab? (i've checked the scilab help file and tutorials,
i'm
still stumped)

Thanks, any help would be much appreciated

[Francois Vogel]

maxpla...@gmail.com said on 15/01/2008 11:33:

> how to
> actually apply this filter to a
> signal in scilab?

See the documentation about signal processing with Scilab:

http://www.scilab.org/doc/signal.pdf

Section 1.8 provides an example with a FIR filter generated with wfir:

[h,hm,fr]=wfir('lp',33,[0.2 0],'hm',[0 0]);
t=1:200;
x1=sin(2*%pi*t/20);
x2=sin(2*%pi*t/3);
x=x1+x2;
hz=syslin('d',poly(h,'z','c')./%z**33);
yhz=flts(x,hz);
plot(yhz)

Francois

[maxpla...@gmail.com]

On Jan 15, 5:59 am, Francois Vogel <fsvogelnew5NOS...@free.fr> wrote:
> maxplanck...@gmail.com said on 15/01/2008 11:33:

I'm a bit of a filter noob, can you recommend a good tutorial that
will explain filter basics and why poly is being used here? I
understand basic properties of filters like cut off frequency, cut off
slope. But i don't understand the inner mathematical workings of them
(i do know euler's identity which shows sin and cos as being composed
of real and imaginary parts, complex envelope etc.)

Thanks a lot

[RRogers]

Are you familiar with Laplace, Fourier, and z transforms?
RayR