H {Dark} | R Documentation |
This is a simple switch function.
Description
This function is used to transition from 'off' to 'on'.
Usage
H(x, k = 100, t)
Arguments
x |
is the measured time. |
k |
is the transition constant, set arbitrarily high. |
t |
is the time at which the transition occurs. |
Details
This helper function used in P5c
and P7c
enables the optim
function to find parameters three times as quickly than if the transitions betwen the phases are modelled by a logical function e.g. a step function.
Value
For times before 't' the output is less than or equal to 0.5, after this time the the output is greater than 0.5. As 'k' grows larger the rate of transition from 0 to 1 increases.
Note
H is a logistic function that maps inputs to a values between zero and one
Author(s)
Jeremiah MF Kelly
Faculty of Life Sciences, The University of Manchester, M13 9PL, UK
References
The logistic function: http://en.wikipedia.org/wiki/Logistic_function
The step function: http://en.wikipedia.org/wiki/Heaviside_step_function
See Also
Examples
x <- seq(0, 20, by=0.1)
k <- 10
t <- 10
op <- par(las=1, bty='n')
## Not run: plot(x,H(x,k,t), 'l')
par(op)