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Re: Equation for controlled fade
Posted:
Oct 23, 2006 1:57 PM


On 23 Oct 2006 03:00:21 0700, "Nick" <Nick.Stansbury@googlemail.com> wrote:
>Hi, > > I'm sure I'm being dumb but I can't think of a way to solve this. Any >help appreciated. > >Given three given values of "Start", "End" and "Length", I need a >function for variables time "T" and values "X" where at T = 1 X=Start >and at T=Length X=End. However if you graph T and X (T along the Y axis >and X along the X axis) I'd like the graph to look something like the >graph of 1/X, i.e. an exponential like "fade" from Start to End over T >periods. > >Hope this makes sense  any ideas appreciated! > >Nick
1/x is not an "exponential". Using the letters:
l = length s = start e = end x = X t = T
try the equation: t = l^( ( x  s) / ( e  s ) )
When x = s you get l^0 = 1 and when x = e you get l^1 = l.
(Here e is just a variable, not the standard calculus e.)
Lynn



