Description Usage Arguments Details Value Author(s) References See Also Examples
frunge provides a sampled numeric solution for an ODE for a given set of values of the independent variable (t). Returns a series of values corresponding to each values of t
1 |
t |
The independent variable. Must be sorted in increasing order |
param |
Numeric vector : under the form of |
y0 |
The initial condition. May appear as a parameter for nls. See details |
Dfdt |
A function giving the right side of the ODE. Default is |
dt |
Time increment for Runge-Kutta algorithm. Must be lower than the smaller difference between two consecutive t values |
graph |
If true, plots the graph of the function over the range of t. (For standalone usage) |
The vector t must be sorted in increasing order. Any badly placed t
will result
in an error and program exit. dt must be lower than min(diff(t))
. If not, an error will occur. The shorter dt, the more accurate the solution but the longer the calculation will be.
A numeric vector of length equal to the length of t. y[1] is set to y0
Jean-Sebastien Pierre
Jean-sebastien.pierre@univ-rennes1.fr
Numerical recipes http://www.nr.com
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | v<-frunge(t=seq(0,50,0.5), param=c(r=0.1,k=100), y0=3, Dfdt = dfdt, dt = 0.01, graph = TRUE)
plot(seq(0,50,0.5),v)
##
## Example of model fitting with frunge. a : determined initial condition
##
data(logis)
attach(logis)
nls(y~frunge(time,c(r,k),y0=3,dfdt,graph=FALSE),data=logis,start=list(r=0.05,k=100),trace=TRUE)->m1
plot(time,y)
lines(time,fitted(m1))
summary(m1)
detach(logis)
##
## Example of model fitting with frunge. b : unknown initial condition ;
## y0 is fitted as a parameter
## Not run: data(logis)
attach(logis)
nls(y~frunge(time,c(r,k,y0),y0,dfdt,graph=FALSE),data=logis,start=list(r=0.05,k=100,y0=y[1]),
trace=TRUE)->m2
plot(time,y)
lines(time,fitted(m2))
summary(m1)
detach(logis)
## End(Not run)
|
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.