[R-sig-finance] fBonds svensson fitting

[Krishna Kumar]

Nelson-siegel and svensson are easy to fit (see 
http://www.bankofcanada.ca/en/res/tr/1999/tr84.pdf)

I used the following test data

 > fwdcrv
   tenor     fwd
1      1 1.10000
2      2 1.11927
3      3 1.13754
4      4 1.15735
5      5 1.22402
6      6 1.26254
7      7 1.33145
8      8 1.40115
9      9 1.47255
10    10 1.62928
11    11 1.69269
12    12 1.81135


And now in R one could do the following:
-------------------------------
nelson<-function(x,y=x)
{
nelson<- sum((y[,2]-(x[1] + (x[2] + x[3]* y[,1])* exp(-x[4]* y[,1])))^2)
}

r = nlm(f=nelson,p=c(1,10,10,10),y=fwdcrv,steptol=1e-10,iterlim=500)

$minimum
[1] 0.6461518

$estimate
[1]  1.361599  8.683838  8.683784 36.325287

$gradient
[1] 1.431076e-08 0.000000e+00 0.000000e+00 0.000000e+00

$code
[1] 1

$iterations
[1] 139

Note svensson is double humped so you have an additional parameter ( 
x[5] ) and so modify the function suitably.
Hope this helps,

Kris






Thomas Steiner wrote:

>I'd like to calculate forward rates from swap rates and then fit these
>fwd-rates to a Svensson family and see how parameters envolve over
>time (consistency).
>I've read of the R-package fBonds, which could help me a lot. It is
>not availible at CRAN or www.metrics.org Does anybody know about its
>current state? Is it available to the public somewhere? Are there any
>other packages that could help me?
>Thanks for suggestions, help and hints
>Thomas
>
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