Description Usage Arguments Details Value Author(s) References See Also Examples
Gompertz equation (Gompertz, 1825). This is equation 2.3 in Table 1.
1 |
time |
a numeric vector of values at which to evaluate the model. |
tmax |
tmax is the time when crop growth rate is maximum and Y = Yo/exp |
theta |
theta determines the curvature |
Yo |
Yo is the max Y |
An alternative way to Richards equation to generate asymetric growth with less parameters Applied to describe water stress index, crop N-uptake, seed germination, crop growth, LAI development, etc. Remark at time = 0, Y is not zero
a numeric vector of length equal to the inputs
Fernando E. Miguez
Nonlinear Regression Models and Applications in Agricultural Research. Sotirios V. Archontoulis and Fernando E. Miguez. Agronomy Journal. doi: 10.2134/agronj2012.0506
1 2 3 4 5 6 7 8 | require(lattice)
## Set parameter values and plot the relationship
time <- seq(0, 150,5)
ans1 <- gompertz(time, tmax = 60, theta = 0.09, Yo=100)
ans2 <- gompertz(time, tmax = 60, theta = 0.07, Yo=100)
ans3 <- gompertz(time, tmax = 60, theta = 0.05, Yo=100)
ans4 <- gompertz(time, tmax = 60, theta = 0.03, Yo=100)
xyplot(ans1 + ans2 + ans3 + ans4 ~ time, type="l", auto.key=TRUE, ylab = "text", xlab = "time")
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