SynthMakertester ·
According to cool edit, this picture is an inverted sine (generated at max gain and no DC modification). What is the mathematics (SM) behind? Without using wavetable.
inv sine (ce stuff again)
From the original SynthMaker forum (2004–2014), with its members’ names and dates.
DigitalWhiteByte ·
math for acos(inverse cosine) function is
streamin x; streamout y; y =(3.14/2)-x-((1/6)*pow(x,3))-((3/40)*pow(x,5))-((5/112)*pow(x,7))-((35/1152)*pow(x,9));
DigitalWhiteByte ·
Both, of course the 16-bit accuracy.
streamin x; streamout acos; streamout asin; acos =(3.1415927/2)-x-((1/6)*pow(x,3))-((3/40)*pow(x,5))-((5/112)*pow(x,7))-((35/1152)*pow(x,9)); asin =x+((1/6)*pow(x,3))+((3/40)*pow(x,5))+((5/112)*pow(x,7))+((35/1152)*pow(x,9));
I hope I did not forget anything.
tester ·
Thanks, I check that when I'm on my second machine; graph and sound will tell. So generally - this equation is an approximate mathematical series? (don't know what is proper translation here - series, string or sequence). Is it the same as the green "sin/cos inverse primitive"?
martinvicanek ·
Yes, DWB's code shows the first terms of the power series for the inverse circular functions arcsin(x) and arccos(x). However, the Cool Edit screenshot seems unrelated to that, looks more like an inverted (in the sense of upside down) rectified sine with DC removed, like
out = a - b*abs(sin(omega*t));
with suitably chosen a and b. (CE draws a smooth curve through the discrete set of samples, hence the overshoots where you would expect kinks). That's my guess anyway, since my version 1.2a of CE does not offer this feature.
tester ·
Tone generator and FFT filter were present up to Adobe Audition v 3.0 (adobe buyed out syntrillium after CE pro was released). However in most recent version (I'm not sure if this is 4.0 or 4.5) - they rebuilded CE from scratch, and removed manu yseful things, like the whole technical tone generator with it's advanced features and as far I remember - FFT filter too.
I don't know what is exactly behind CE inv sine, but it sounds nice 🙂 So I thought to include it (as a handy shape selection) in my gadged too. By the way - are there any other basic shapes, that are sounding nice, and are related to some basinc mathematical functions? I'm including a wavetable (and slow-noise modifiers) too, but shape loader is a different story there.
tester ·
Hmm... I have no sound on output, neither with frequency input in (0-1) normalized range nor in stanradrd Hz range. So I guess this is not the equivalent of inv sine from cool edit or something is missing here.
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