>*if* (and you haven't answered this "if" question yet), your data >points (that you are interpolating between) are equally spaced in >time, you can use a table that small (or even smaller, if you're >comparing to 3rd-order hermite) along with linear interpolation >between the finite number of fractional delay points that the table >hits. you still have complete random addressing. but you have to >divide your fractional delay address into two parts (which is easy if >you have the number of fractional delays in your table is a power of >two - you simply mask the bits). the most-significant part is used to >decide which entries in you table to use to interpolate. the least- >significant part is used to do linear interpolation between these very >closely spaced fractional delays. > >now *that* works for data points that are equally (or "uniformly") >spaced. are your data points uniformly spaced? if so, your life can >be made much easier, no matter how you do your interpolation.I'm not sure if I understand this. I want it to be accessed randomly, so no equal spacing, any fractional number. And the control points (between which are interpolating) may have absolutely any position.>> Imaging an envelope in range 0..1, where >> 0..0.49 is constant, 0.51..1 is constant and there are many points in >> between. To represent this accurately you need the table to be verylarge>> to represent all those points, because it may e.g. be addressed with >> precision of 0.00001 in X. And this would take a lot of time togenerate>> (which is not possible), the table would be very large and in thereforei=>t >> would take a lot of memory, which would be too slow in this case.Imagine an A4 paper on desk in front of you directed horizontally. Take a pen an paint some points. You can paint them anywhere. And now you have several control points, one border of the paper is X axis, the second one Y. And you want to be able to get Y value for any X. If you have painted many control points let's say around the center X but with very different Y (10 dots in the center top, 10 dots in the center bottom), the interpolated function will look like a big mess in there and you will need at least some values in the lookup table corresponding to the interval between them to define the values correctly. Since there is teoretically no limit between the distance of neighbouring points, there is no way you can create a look table - except having a lookup table for each pair of neighbours and what is the advantage of it then? (I mean against using cubic curve directly)>you're gonna have to re-explain this for me to understand you. > >> But I think everything is okay now ;-). >> I hope this was understandable :-). > >not all of it was.Yeah, I couldn't be a teacher :-))) dmnc.