Displaying 2 results from an estimated 2 matches for "gamma_inc".
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2005 May 05
2
Precision in R
Could anyone help me with the following issue.
Using the GSL library in R I define the following code:
#########
library(gsl);
S<-function(n)
{ r<-0:n;
ans<-sum(gsl_sf_choose(n,r)*(-1)^r*2^(2*r)*gamma_inc(6-2*r,2))
ans }
#########
>SS(10) yields 34.91868
>SS(40) yields 5.340422
>SS(60) yields 180.3162
Doing the same computations in maple I get
34.918679360927169740821310620770402166885975646756
5.340473872869891061658721253647686930049562214921
2.2269219454888559341895277572725106...
2007 Aug 30
2
Incomplete Gamma function
Hello
I am trying to evaluate an Incomplete gamma function
in R. Library Zipfr gives the Igamma function. From
Mathematica, I have:
"Gamma[a, z] is the incomplete gamma function."
In[16]: Gamma[9,11.1]
Out[16]: 9000.5
Trying the same in R, I get
> Igamma(9,11.1)
[1] 31319.5
OR
> Igamma(11.1,9)
[1] 1300998
I know I have to understand the theory and the math
behind it rather