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Exponential curve for

Type : Exponential curve
References : Posted by neolit123 [at] gmail [dot] com

Notes :
When you design a frequency control for your filters you may need an exponential curve to give the lower frequencies more resolution.


Case (control middle point):

Ploted diagram with 5 points:

Code :
//tweak - 14.15005 to change middle point and F(max)
F = 19+floor(pow(4,x/14.15005))+x*20;


Added on : 30/10/08 by neolit123[ AT ]gmail[ DOT ]com
Comment :
same function with the more friendly exp(x)

y = 19+floor(exp(x/10.2071))+x*20;

middle point (x=50) is still at 1135hz

Added on : 30/10/08 by neolit123[ AT ]gmail[ DOT ]com
Comment :
Here is another function:
This one is much more expensive but should sound more linear.

//t - offset
//x - 0-100%
//y - 20-20000hz

t = 64.925;
y = floor(exp(x*log(1.059))*t - t/1.45);

Comparison between the two:

Added on : 01/11/08 by neolit123[ AT ]gmail[ DOT ]com
Comment :
Yet another one! :)
This is one should be the most linear one out of the 3. The 50% appears to be exactly the same as Voxengo span midpoint.

//x - 0-100%
//y - 20-20k

y = floor(exp((16+x*1.20103)*log(1.059))*8.17742);

//x=0, y=20
//x=50, y=639
//x=100, y=20000

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