How to Write This Function 
March 22nd, 2009, 05:52 PM
| | Member | | Join Date: Nov 2008
Posts: 80
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Hi,
I have a function y=1/x but I need it to return values like:
y=1.0 --> x=1.0
y=0.5 --> x=1.5
I guess I need a logarithmic function but how?
Thanks.
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March 22nd, 2009, 06:15 PM
|  | Expert | | Join Date: Mar 2007
Posts: 10,634
Provided Answers: 2 | | | re: How to Write This Function
Quote:
Originally Posted by serdar  Hi,
I have a function y=1/x but I need it to return values like:
y=1.0 --> x=1.0
y=0.5 --> x=1.5
I guess I need a logarithmic function but how? | Any function that goes through those two points (1.0,1.1.0) and (1.5, 0.5) will do, even a simple linear function f(x) == 2-x would do fine. What exactly do you want?
kind regards,
Jos
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March 22nd, 2009, 06:27 PM
| | Member | | Join Date: Nov 2008
Posts: 80
| | | re: How to Write This Function
I have a multiplier variable that changes based on a percentage value. With my current function (y=1/x) when we have 50% the multiplier is 2, which is too high for me.
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March 22nd, 2009, 06:33 PM
| | Expert | | Join Date: Mar 2007
Posts: 10,634
Provided Answers: 2 | | | re: How to Write This Function
Quote:
Originally Posted by serdar I have a multiplier variable that changes based on a percentage value. With my current function (y=1/x) when we have 50% the multiplier is 2, which is too high for me. | What would the values f(0) and f(infinity) be for your function?
kind regards,
Jos
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March 22nd, 2009, 06:52 PM
| | Member | | Join Date: Nov 2008
Posts: 80
| | | re: How to Write This Function
Well the multiplier is actually a 'gain' value depends on the volume. So if the volume is 0 there is no need to calculate the gain.
gain=1/volume; (where volume>0 and volume<=1)
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March 23rd, 2009, 04:09 PM
| | Moderator | | Join Date: Mar 2006
Posts: 1,103
| | | re: How to Write This Function
x = - log(y) + 1 ??
y = 1 -> x = 1
y = .5 -> x = 1.30
y = .2 -> x = 1.70
or
x = -ln(y) + 1 ??
y = 1 -> x = 1
y = .5 -> x = 1.69
y = .2 -> x = 2.61
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April 12th, 2009, 03:04 AM
| | Member | | Join Date: Nov 2008
Posts: 80
| | | re: How to Write This Function
Thanks jkmyoung, I'll look deeper into that when I'm back working on the project.
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