Butterworth filter in MATLAB: zero lag?

I am wondering if MATLAB uses a bidirectional filter (zero lag) for butterworth lowpass filtering?

Answer 1

[Jan]

fc    = 300;
fs    = 1000;
[b,a] = butter(6,fc/(fs/2), 'low');
yy    = filtfilt(b, a, y)

If you ask an internet search engine for "MATLAB uses a bidirectional filter zero lag", the docs of filtfilt are the 2nd match after your own question. See also doc butter.

[Matilda]

Oh how did I miss that! Thank you very much for you help.