Help Growth Models - Derivates

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The discussion revolves around the challenges faced in deriving the Gauss growth model for an agricultural study on onion growth parameters. The user seeks clarification on the correct derivative of the Gauss function, specifically Y= α e^{-k(t-γ)^2}, and expresses confusion regarding the representation of parameters in derivatives compared to other models like Monomolecular, Logistic, and Richards. A response provides the correct derivative and emphasizes that the differences in the logistic and Richards models are mainly in the constants' representation. The user remains uncertain about the inclusion of parameters in the derivative and seeks further understanding. Overall, the conversation highlights the complexities of applying mathematical growth models in agronomy.
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Hi! I am amateur in mathemathicals growth models but I am doing my graduated work in adjust five differents models in some growth parameters in onion,

[PLAIN]http://img820.imageshack.us/img820/2929/models.png

So my doubt is basically in a derivate for gauss model, i can't derivate this model and it had been adjust for some parameters. So i need to know a derivate for continue my growth analysis.

Also, I just don't know if a sentence of that model is right or wrong, same for others models and their derivates. I read some books about nonlinear models and found diferents expressions in Monomolecular, logistic and Richards models, so i put as options (1 and 2). I also have doubt which are right.

Im grateful with your helps. I'm not physics student, I'm agronomist so you could know better,

Thanks,
 
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If you just go ahead and differentiate the Gauss function, Y= \alpha e^{-k(t-\gamma)^2} you get <br /> \frac{dY}{dt}= -2k\alpha (t- \gamma)e^{-k(t-\gamma)^}<br /> which is the same as<br /> \frac{dY}{dt}a= -2k(t- \gamma)Y<br /> <br /> I see no difference at all between your &quot;options&quot; for the Logistic Equation and only differences in the way the constants are written for the exponential and Richards equations.
 
Fixed the LaTeX for readability.
HallsofIvy said:
If you just go ahead and differentiate the Gauss function, Y= \alpha e^{-k(t-\gamma)^2} you get
\frac{dY}{dt}= -2k\alpha (t- \gamma)e^{-k(t-\gamma)^}
which is the same as
\frac{dY}{dt}a= -2k(t- \gamma)Y

I see no difference at all between your "options" for the Logistic Equation and only differences in the way the constants are written for the exponential and Richards equations.
 
Thanks Mr. Hall,

But i don't know if I am wrong but when you showed a derivate, it should be dY/dt so i don't understand but parameters as gama and t shouldn't be in the derivate as you can see as others models.

I hope you could understand,
 
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