Question

I have to make filter, this is my code:

octave:1> x=randn(500);
octave:2> b=fir1(50,0.2,'stop',boxcar(51));
error: `boxcar' undefined near line 2 column 22
error: evaluating argument list element number 4

What is problem here?

Also Low-pass filter is ‘low’ or ‘stop’ in Octave?

@edit
New error:

octave:2> b=fir1(50,0.2,'stop');
error: `fir1' undefined near line 2 column 3

is it possible I don’t have something?

Answer 1

From the man page:

usage: b = fir1(n, w [, type] [, window] [, noscale])

You probably want e.g.:

b=fir1(50, [0.1 0.2], 'stop');