# Expint

From gsl v2.1-6
0th

Percentile

##### exponential functions

Expint functions as per the Gnu Scientific Library, reference manual section 7.17 and AMS-55, chapter 5. These functions are declared in header file gsl_sf_expint.h.

Keywords
array
##### Usage
expint_E1(x, give=FALSE, strict=TRUE)
expint_E2(x, give=FALSE, strict=TRUE)
expint_En(n, x, give=FALSE, strict=TRUE)
expint_Ei(x, give=FALSE, strict=TRUE)
Shi(x, give=FALSE, strict=TRUE)
Chi(x, give=FALSE, strict=TRUE)
expint_3(x, give=FALSE, strict=TRUE)
Si(x, give=FALSE, strict=TRUE)
Ci(x, give=FALSE, strict=TRUE)
atanint(x, give=FALSE, strict=TRUE)
##### Arguments
x

input: real values

n

input: integer values

give

Boolean with TRUE meaning to return a list of three items: the value, an estimate of the error, and a status number

strict

Boolean, with TRUE meaning to return NaN if status is an error

##### Note

Function expint_En() requires GSL version 1.8 or later.

##### References

http://www.gnu.org/software/gsl

• Expint
• expint
• expint_E1
• expint_E2
• expint_En
• expint_Ei
• Shi
• Chi
• expint_3
• Si
• Ci
• atanint
##### Examples
# NOT RUN {
x <- seq(from=0.5, to=1, by=0.01)
cbind(x,Si(x),Ci(x),expint_Ei(x),expint_E1(x))  #table 5.1 of AS, p239

x <- seq(from=0, to=12, len=100)
plot(x,Ci(x),col="black",type="l",xaxt="n",yaxt="n",bty="n",
xlab="",ylab="",main="Figure 5.6, p232",
xlim=c(0,12),ylim=c(-1,2.0))
lines(x,Si(x))
axis(1,pos=0)
axis(2,pos=0)
abline(h=pi/2,lty=2)

# Table 5.4, page 245:
xvec <- seq(from=0,by=0.01,len=20)
nvec <- c(2,3,4,10,20)
x <- kronecker(xvec,t(rep(1,5)))
n <- kronecker(t(nvec),rep(1,20))
ans <- cbind(x=xvec,expint_En(n,x))
rownames(ans) <- rep(" ",length(xvec))
colnames(ans) <- c("x",paste("n=",nvec,sep=""))
class(ans) <- "I do not understand the first column"

ans

# }

Documentation reproduced from package gsl, version 2.1-6, License: GPL-3

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