Theformand

Im looking for some help on some general math here.

Basically I have a patch, where I get a range of input values (from sensors). This range is from 0.06 - 0.958

Now, i want to convert this range to notes. I have to use these values in the abovementioned range to stretch across 12 notes, from A (440Hz) to G#(830,61Hz). The big problem for me is that im no musical genius or a math wiz by any stretch of the imagination.

I need help with a transfer function that will follow the note scale from A-G#. The big problem for me is that as soon as anything goes non-linear (notes arent equally spread on the scale), im deaf and blind. If anyone could help me with a transfer function that will spit out the correct numbers so I can hook those up to my oscillators that would be so much appreciated.

Please let me know if any of this is unclear.

Im looking for some help on some general math here.
Basically I have a patch, where I get a range of input values (from sensors). This range is from 0.06 - 0.958
So my range is 0.898.

I need help with a transfer function that will follow the note scale from A-G#. The big problem for me is that as soon as anything goes non-linear (notes arent equally spread on the scale), im deaf and blind. If anyone could help me with a transfer function that will spit out the correct numbers so I can hook those up to my oscillators that would be so much appreciated.
Please let me know if any of this is unclear.
-Theformand


kinda-tricky-scaling-regarding-notes

Basically you want to map the number range to an exponential 

function. y = x^2 * 0.898. Your input values will be x = 0. to

1., the output of that will be mapped on to the range 0.898.

If you then scale your key values between 0. - 1. (using scale), 

Here is one way to do it...
Basically you want to map the number range to an exponential 
function. y = x^2 * 0.898. Your input values will be x = 0. to
1., the output of that will be mapped on to the range 0.898.
If you then scale your key values between 0. - 1. (using scale), 
you should get what you are looking for.

you need 2 objects for such a conversion, unless you 

[expr ((($f1-0.06)/(0.958-0.06))*(830,61-440))+440],

you need 2 objects for such a conversion, unless you 
want to program your own.

Here's a patch which lets you set an exponent, then gets the resulting values by sending a list of numbers from 0. to 1. through the function. You can specify the number of points that get calculated, or send single values with a slider. The results are put in an itable and scaled to fit the table range of 0-127.

Exponent values like 0.4 can be good for setting gainfader~ from a linear source, like a slider with 0-127 values. You can also use them for velocity curves or anywhere you want non-linear scaling, just save a bunch of table presets. Lots of other curve-making functions are possible, they just need the right scaling for the table range.

The default exponent is 2, so you get the right half of the parabola y = x^2. a value of 1 gives a line.

Off cuff: [lp.scampi map 0.06 0.958 57 68 exp]

The lp.scampi help file will give you a nice graphic showing how input maps to output.

Peter Castine wrote on Fri, 29 May 2009 13:34

Gotta run, pizza's burning......Pizza's burnt. Yum.

With all due modesty, lp.scampi's help file is the most useful way of visualizing what the results of a mapping will do, particularly for those who don't do exponents in their head. And the object has more options than any of the factory scaling objects.

lp.scampi is part of the free Litter Starter Pack, available at the URI below. Note that the Starter Pack is still at package version 1.7, which is happier with Max 4.x. It does actually work with Max 5, but there are a lot of confusing warnings msgs and some issues w/the help files. For true Max 5 bliss you'll need Litter Pro.

Peter Castine wrote on Fri, 29 May 2009 13:34Off cuff: [lp.scampi map 0.06 0.958 57 68 exp]

lp.scampi is part of the free Litter Starter Pack, available at the URI below. Note that the Starter Pack is still at package version 1.7, which is happier with Max 4.x. It does actually work with Max 5, but there are a lot of confusing warnings msgs and some issues w/the help files. For true Max 5 bliss you'll need Litter Pro.


Kinda tricky scaling regarding notes