Forums > MaxMSP

How to make exponential data curves?

March 31, 2008 | 4:24 am

Hi, I am Peter Ostry, I am new in this forum and new to Max. Please excuse me if my questions are "common knowledge".

I am looking for the best way to let a slider run
- from 0-90 and stop
- or from 90-0 and stop
- with adjustable speed
- following several selectable exponential curves

I looked into the "bline" object and it seems to do what I want. I can load different lists to control the curve and the direction. But I am a bit unsure if I chose the right technique. I don’t need ultrasmooth operation but writing the lists is rather tedious. And I need a couple of them and one set for for each direction. Is there another way to create exponential curves?

I think there must be a formula but I don’t know which one (I am lousy in maths) nor do I know how and in which object to use it. If someone knows a trick for easy creation of exponential curves, I appreciate any suggestion or hints where to look in the Max manual.


March 31, 2008 | 5:48 am

hey

I would use just a line going from one number to the next over a
chosen time and feed it into an [expr] containing the formula with the
one below being the easiest
maybe you can get a [expr $f1 * pow($f1,1)] you can change the last
number by substituting it with $f2 to get a faster or slower
exponential function

hope this helps

On 31 Mar 2008, at 06:24, Peter Ostry wrote:

>
> Hi, I am Peter Ostry, I am new in this forum and new to Max. Please
> excuse me if my questions are "common knowledge".
>
> I am looking for the best way to let a slider run
> – from 0-90 and stop
> – or from 90-0 and stop
> – with adjustable speed
> – following several selectable exponential curves
>
> I looked into the "bline" object and it seems to do what I want. I
> can load different lists to control the curve and the direction. But
> I am a bit unsure if I chose the right technique. I don’t need
> ultrasmooth operation but writing the lists is rather tedious. And I
> need a couple of them and one set for for each direction. Is there
> another way to create exponential curves?
>
> I think there must be a formula but I don’t know which one (I am
> lousy in maths) nor do I know how and in which object to use it. If
> someone knows a trick for easy creation of exponential curves, I
> appreciate any suggestion or hints where to look in the Max manual.
>


March 31, 2008 | 7:47 am

Yes it helped, much easier. Thanks.
Just one problem due to my lack of mathematical knowledge:
It works now as I need it but it starts always slow and accellerates on the way. Can I reverse that, to let it start fast and become slower? I tried 0.5 as the last number in the formula and less, but I don’t see much of a difference. Negative numbers do not work.

Quote: pieter.coussement wrote on Sun, 30 March 2008 23:48
—————————————————-
> I would use just a line going from one number to the next over a
> chosen time and feed it into an [expr] containing the formula with the
> one below being the easiest
> maybe you can get a [expr $f1 * pow($f1,1)] you can change the last
> number by substituting it with $f2 to get a faster or slower
> exponential function
>
> hope this helps
>
>
> On 31 Mar 2008, at 06:24, Peter Ostry wrote:
> > I am looking for the best way to let a slider run
> > – from 0-90 and stop
> > – or from 90-0 and stop
> > – with adjustable speed
> > – following several selectable exponential curves


March 31, 2008 | 8:39 am

A nice no-brainer for curves is Tristan Jehan’s mapper
object – see http://web.media.mit.edu/~tristan/
(Mac-only, atm, I’m afraid…)
cheers
Roger

— Peter Ostry

wrote:

>
> Hi, I am Peter Ostry, I am new in this forum and new
> to Max. Please excuse me if my questions are "common
> knowledge".
>
> I am looking for the best way to let a slider run
> – from 0-90 and stop
> – or from 90-0 and stop
> – with adjustable speed
> – following several selectable exponential curves
>
> I looked into the "bline" object and it seems to do
> what I want. I can load different lists to control
> the curve and the direction. But I am a bit unsure
> if I chose the right technique. I don’t need
> ultrasmooth operation but writing the lists is
> rather tedious. And I need a couple of them and one
> set for for each direction. Is there another way to
> create exponential curves?
>
> I think there must be a formula but I don’t know
> which one (I am lousy in maths) nor do I know how
> and in which object to use it. If someone knows a
> trick for easy creation of exponential curves, I
> appreciate any suggestion or hints where to look in
> the Max manual.
>


March 31, 2008 | 8:55 am

Another let-the-object-do-the-thinking approach are lp.scampf and lp.scampi from Litter Power. These run on both Mac OS and Windows and give you more curve variations than anything else: exponential, parabolic, logarithmic, S-curves, U-curves, linear with a "kink" point…

Part of Litter Starter Pack, available at the URL below.

Best,
Peter


March 31, 2008 | 8:33 pm

Quote: roger.carruthers wrote on Mon, 31 March 2008 02:39
—————————————————-
> A nice no-brainer for curves is Tristan Jehan’s mapper
> object – see http://web.media.mit.edu/~tristan/
> (Mac-only, atm, I’m afraid…)

Thanks, this seems to be what I need for now.
And I am also Mac-only, so we fit together.

The Litter Pack looks also interesting, but is a bit too big for me. I don’t want to start with many externals. I am pretty sure that I would make a big mess until I discover how to organize my Max work. Basics and just few and little helpers are more important at the moment.


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