Expint | R Documentation |
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
.
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)
x |
input: real values |
n |
input: integer values |
give |
Boolean with |
strict |
Boolean, with |
Function expint_En()
requires GSL version 1.8 or later.
Robin K. S. Hankin
https://www.gnu.org/software/gsl/
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
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