[R] recursive term
Roslina Zakaria
zroslina at yahoo.com
Wed Dec 10 06:28:28 CET 2008
Hi,
I would like to write a function for this formula:
F(a,b,c,z)=1+(ab)/(1!c)+ +(a(a+1)b(b+1))/(2!c(c+1))+ +(a(a+1)(a+2)b(b+1)(b+2))/(3!c(c+1)(c+2))+…
I wrote this function but not sure what is not right:
hypergeo_sum <- function (a,b,c,z,n)
{ for (i in 1:n)
{ aa <- 1+(a*b*z)/c
aa[i] <- (aa-1)*(a+i)*(b+i)*z/((i+1)*(c+i))
comb_sum <- aa + aa[i]+ aa[i+2]
}
comb_sum
}
hypergeo_sum (1.25,1.75,1.25,0.5,3)
output:
> hypergeo_sum (1.25,1.75,1.25,0.5,3)
[1] 2.394531 NA 1.039062
The answer should be 2.852539.
Or can you suggest any R book that I can refer to. Thank you so much for your help.
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