On Fri, 22 Oct 2010, Martin Schied wrote:

I wanted to use a fairly high a < 1 because then the phase for all frequencies is approximately 90° off like for the ideal a=1. Using slightly smaller factors and comparing input / output didn't satisfy my expectations. maybe that would't matter at all - let's experiment...

How is the phase preservation an important thing for you ? I ask because I didn't really think of it as important... (and I still somewhat don't know when it's really important).

that's indeed interesting. So the gain is defined for a constant signal having the same input and output samples (or in other words DC having no amplification) if I understood it correctly.

It's defined for any signal. There are different equivalent ways to define the gain of a linear filter. In my head, I was thinking of an input signal containing a single 1 in a sea of zeroes... but it might be a bit easier to understand it using a constant input signal. Then for [sig~ 1], [rpole~ 1] will diverge (as much as the float32 number format can allow it to...) because 1/(1-1) is undefined (it's a division by zéro). But for [sig~ 1] again, [rpole~ 0.999] will output a constant 1000.