Help Growth Models - Derivates

[acocac]

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,

 

[HallsofIvy]

If you just go ahead and differentiate the Gauss function, [itex]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.

 

[Mark44]

Fixed the LaTeX for readability.

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.

 

[acocac]

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,

 

[CellCoree]

Hello,

Thank you for reaching out for help with your growth models and derivatives. I understand the importance of accurately representing and analyzing data in order to make meaningful conclusions.

To address your question about the derivative for the gauss model, it would be helpful to know what specific parameters you are adjusting and how you are fitting the model to your data. The derivative for the gauss model depends on the specific form of the model and the parameters being adjusted. It may be helpful to consult with a mathematician or statistician for assistance with this specific problem.

As for the other models, it is important to carefully check the equations and expressions to ensure that they are correct. This can be done by comparing them to other sources and consulting with experts in the field. It is also important to consider the assumptions and limitations of each model in order to choose the most appropriate one for your data.

I hope this helps and wish you success in your graduate work. Don't hesitate to reach out for further assistance if needed.

Best,