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Regression Analysis for Channel Routing

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chicopee

Mechanical
Joined
Feb 15, 2003
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6,199
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My regression analysis program that I developed in BASICS back in the 1980's applies for half a dozen equations. I would like to update my program to include this form: I(t)=P*(t^s)*(e^(-ft)) which I can transform it to this equivalent non- linear log form: Ln I(t)=Ln P + s*Ln t + (-ft); P,s and f are constants. Is there any way to take care of the term (-ft). I got 18 data points avaialble for this regression analysis.
 
I don't understand what you're trying to do BUT:

isn't y= x^-n the same as
y= 1/x^n ?
 
Yes to your equation.
I am trying to determine the values of constants of P,s and f of the Gama function I(t)=P*(t^s)*(e^(-ft)). t is for time; I(t)has values of cu.ft/sec or cu.m./sec. My computerized regression analysis is linear equations. Unfortunately the Gamma function turns out to be non-linear so beside trial and error how can I handle this non linear expression with regression analysis?

Here is another thought. Since I have 18 data points (flow vs time), can I solve theses constants with matrices using this transformation: Ln I(t)=Ln P + s*Ln t + (-ft) eventho I would have 18 rows and 4 columns?
 
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