What does this signal filter do? (coming from finance)
I thought you stock market tech analysts always used moving averages (rolling means) or "exponential moving averagers" for your smoothing operations. Anyway, your $macd[n]$ process is neither of those. As far as I can tell the frequency magnitude response of your $macd[n]$ process looks like the following:



Your $macd[n]$ process does not smooth its input data in the normal sense. It amplifies input data that has a periodicity (repetition rate) of 33.3 days per cycle. In the above plot you can clearly see the "mainlobe" that Fat32 was referring to. If your closing price data contains a periodicity of roughly 33 days then the output of your $macd[n]$ process will be a large value. Otherwise, the output of your $macd[n]$ process will be a small value. I don't know if such a frequency response makes stock market technical analysis sense, or not. 

As for your $h[n]$ process, I believe its frequency magnitude response looks like the following:



Your $h[n]$ process appears to be a process that amplifies input data that has a periodicity (repetition rate) of 21.9 days per cycle. In DSP we use processes like your $macd[n]$ and $h[n]$ for filtering when we want to detect the presence of components in our input signal that have periodicities of 33.3 or 21.9 time units per repetition. We call such processes "resonators" or "bandpass filters."