How to find the exponential decay function

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I am studying bioinformatics. I am trying to solve a problem. So we have a gene, whose initial value $x_0$ at time $t = 0$ is $x_0 = 1$. A perturbation of factor $-0.9789812$ is applied to it, such that, at time $t = 10$, its value is $0.0210359$. The gene is measured at time-points $t = [0,1,2...,10]$. How can I know the calculate the values at time $t = 1,2,...,10$, given the only information I have is the value at $x_0$ and and the perturbation applied ? I am giving the data here

$x = [ 1.0000000 ,0.3482754, 0.1304151, 0.0575881, 0.0332433, 0.0251052, 0.0223848, 0.0214755, 0.0211715, 0.0210698, 0.0210359]$

But I want to know how would I generate this data. I tried the exponential decay function and the values do not correspond to the ones I have in my data set.

So if the gene has an initial value of 1 and a perturbation of −0.9789812 is applied to it, at the final reading of the gene at time t = 10 is 1−0.9789812 = 0.0210188. The decay is not linear, it seems like it has an exponential curve but I dont know how to fit it. Note that the only information I have is the initial value of the gene, the perturbation applied. I want to be able to calculate the values of gene at any time given this information.

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Even if your model is correct and exponential decay is expected, real work data rarely fits perfectly.

I expect that you are familiar with cases of linear relationships e.g. $y = ax$ or $y = ax + b$. In these cases, you could plot the points on a graph and find the line of best fit.

If the expected relationship is $y = e^{-ax}$ then this does not work but note that $\log(y) = -ax$ so the relationship between $\log(y)$ and $x$ is linear. So, plot $\log(y)$ rather than $y$ and try to find the line of best fit.