self start for Beta Growth Function
Self starter for Beta Growth function with parameters w.max, t.m and t.e
bgf(time, w.max, t.e, t.m) SSbgf(time, w.max, t.e, t.m) bgf2(time, w.max, w.b, t.e, t.m, t.b)
time |
input vector (x) which is normally ‘time’, the smallest value should be close to zero. |
w.max |
value of weight or mass at its peak |
t.e |
time at which the weight or mass reaches its peak. |
t.m |
time at which half of the maximum weight or mass has been reached. |
w.b |
weight or biomass at initial time |
t.b |
initial time offset |
For details see the publication by Yin et al. (2003) “A Flexible Sigmoid Function of Determinate Growth”.
The form of the equation is:
w.max * (1 + (t.e - time)/(t.e - t.m)) * (time/t.e)^(t.e / (t.e - t.m))
. Given this function weight is expected to decay and reach zero again at 2*t.e - t.m.
bgf: vector of the same length as x (time) using the beta growth function
bgf2: a numeric vector of the same length as x (time) containing parameter estimates for equation specified
## See extended example in vignette 'nlraa-AgronJ-paper' x <- seq(0, 17, by = 0.25) y <- bgf(x, 5, 15, 7) plot(x, y)
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