R: exponential functions

Expint {gsl} | R Documentation

## exponential functions

### Description

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`.

### 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.

### Author(s)

Robin K. S. Hankin

### References

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

### Examples

    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

[Package gsl version 2.1-6 Index]