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Asked by Tom
on 27 Feb 2012

Hi, I'm having problems finding something out something simple.

If I'm given this: -

[b,a] = cheby1(8,1,0.4); y = filter(b,a,x);

then what do the three digits in the brackets after 'cheby1' mean?

Also what does b, a and x mean?

Many thanks,

Tom

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Answer by Kevin Holst
on 27 Feb 2012

Accepted answer

Chebyshev Type 1 filter design

http://www.mathworks.com/help/toolbox/signal/ref/cheby1.html

1-D digital filter

Answer by Honglei Chen
on 27 Feb 2012

This is clearly explained in documentation.

doc cheby1

http://www.mathworks.com/help/toolbox/signal/ref/cheby1.html

`x` is the input signal, also see the doc

doc filter

## 2 Comments

## Matt Fig

Direct link to this comment:http://nl.mathworks.com/matlabcentral/answers/30410#comment_108878

Hi, I'm having problems finding something out something simple.

If I'm given this: -

[b,a] = cheby1(8,1,0.4); y = filter(b,a,x);

then what do the three digits in the brackets after 'cheby1' mean?

Also what does b, a and x mean?

Many thanks,

Tom

## Matt Fig

Direct link to this comment:http://nl.mathworks.com/matlabcentral/answers/30410#comment_108915

Tom's questionHi, I'm having problems finding something out something simple.

If I'm given this: -

[b,a] = cheby1(8,1,0.4); y = filter(b,a,x);

then what do the three digits in the brackets after 'cheby1' mean?

Also what does b, a and x mean?

Many thanks,

Tom