similar to: integrate() and complex values

Hi When using Sweave, most of my functions get called with complex arguments. They get typeset in with additions that I don't want; "1+1i" appears as "1 + (0 + 1i)" and I would rather have plain old "1+1i". Example follows: \documentclass[a4paper]{article} \title{A Test File} \author{Robin Hankin} \usepackage{a4wide} \begin{document} \maketitle A

The following caught me off-guard: R> z <- 1i + 1:10 R> z <- Re(z) R> z [1] 1 2 3 4 5 6 7 8 9 10 as expected. But look: R> z <- 1i + 1:10 R> make.real <- abs(z) < 1000 R> z[make.real] <- Re(z[make.real]) R> z [1] 1+0i 2+0i 3+0i 4+0i 5+0i 6+0i 7+0i 8+0i 9+0i 10+0i R> didn't make z a real vector, which is what I wanted.

Hi If x <- 1:10 then x[5] <- 1i will promote x to be a complex vector. Suppose I have an S4 class "brob", and have functions is.brob(), as.brob(), as.numeric() and so forth (minimal self-contained code below). If x is numeric (1:10, say) and y is a brob, what is the best way to make x[5] <- y promote x to a brob in the same way as the complex example? Or is

Hi If I have a <- Inf + 1i then Re(a) is Inf, and Im(a) is 1, as expected. But if b <- 1 + Inf * 1i, then Im(b) = Inf , as expected, but Re(b) = NaN, which I didn't expect. Why this asymmetry? How to define an object with Re(b)=1, Im(b)=Inf? -- Robin Hankin Uncertainty Analyst Southampton Oceanography Centre European Way, Southampton SO14 3ZH, UK tel 023-8059-7743

Hi ?atan2 says that atan2(y,x)=atan(y/x) for x and y numeric or complex vectors. Well, I would expect atan2(1,1i) to be equal to atan(-1i), but > atan2(1,1i) Error in atan2(y, x) : Non-numeric argument to mathematical function > R.version _ platform powerpc-apple-darwin8.5.0 arch powerpc os darwin8.5.0 system powerpc, darwin8.5.0

Hi ?atan2 says that atan2(y,x)=atan(y/x) for x and y numeric or complex vectors. Well, I would expect atan2(1,1i) to be equal to atan(-1i), but > atan2(1,1i) Error in atan2(y, x) : Non-numeric argument to mathematical function > R.version _ platform powerpc-apple-darwin8.5.0 arch powerpc os darwin8.5.0 system powerpc, darwin8.5.0

Hi has anyone coded up domain colouring for visualizing complex analytic functions (such as elliptic functions)? [ the idea is to depict a complex function f(z) using a filled.contour() variant in which the hue is given by Arg(f(z)), and the saturation by Mod(f(z)). ] -- Robin Hankin Uncertainty Analyst Southampton Oceanography Centre European Way, Southampton SO14 3ZH, UK tel

Hello everybody I'm using contour() to draw streamlines of potential flow, eg jj <- seq(from= -4, to=4,len=20) jj <- outer(jj,jj,function(x,y){x})+1i*outer(jj,jj,function(x,y){y}) f <- function(x){x^2} contour(Im(f(jj)), nlevels=44 , labels="") How best to put arrows on the contour lines to show the direction of flow? (ie I want contour lines looking like

Hi. I want to use image() with colours that are indexed by two variables. Indexing by one variable is easy: library(colorspace) x <- seq(from=0, to=1,len=30) z <- outer(x,1i*x,"+") image(Re(z),col=hcl(seq(from=0,to=100,len=15),c=100)) OK, so far so good. Now, I want the colour to be a more complicated function of z, in which both the hue and luminance change (thus the colours

Hello everyone I am finding complex numbers to be printed oddly in R-alpha. > 1e100+1e100i [1] 1e+100+1e+100i > 1e100 + 1e44i [1] 1e+100+100000000000000008821361405306422640701865984i > dput(1e100+1e44i) 1e+100+100000000000000008821361405306422640701865984i > [same thing at home on a linux box] The first line is what I would expect, the second and third lines aren't: I

Hi try this: p3dpairs <- function(x,x1, xlim=NULL,ylim=NULL,zlim=NULL,col=par("col"), pch=par("pch"), cex=par("cex"), ...){ if(is.matrix(x)){ z <- x[,3] y <- x[,2] x <- x[,1] } if(is.matrix(x1)){ z1 <- x1[,3] y1 <- x1[,2] x1 <- x1[,1] } if(missing(zlim)) { z.grid <-

Hello List does anyone have an R function for the Lambert W function? I need complex arguments. [the Lamert W function W(z) satisfies W(z)*exp(W(z)) = z but I could'nt even figure out how to use uniroot() for complex z] -- Robin Hankin Uncertainty Analyst Southampton Oceanography Centre SO14 3ZH tel +44(0)23-8059-7743 initialDOTsurname at soc.soton.ac.uk (edit in obvious way; spam

Hello everyone before I reinvent the wheel, has anyone out there coded up the gamma() function for complex arguments? -- Robin Hankin Uncertainty Analyst Southampton Oceanography Centre SO14 3ZH tel +44(0)23-8059-7743 initialDOTsurname at soc.soton.ac.uk (edit in obvious way; spam precaution)

Hi One of my packages needs a look-up table of pre-calculated numbers in the data directory. I would like to have the matrix as large as possible. What is the largest size matrix that would be an acceptable datafile in an R package? [ The table is a square, upper triangular matrix consisting of logs of Stirling numbers calculated by Maple. As discussed on the List a few days ago (thanks

Hi ?lines says For 'type = "h"', 'col' can be a vector and will be recycled as needed. Why doesn't lines() recycle colours for other types? If I type > plot(0:1,0:1,type="n") > lines(runif(11),runif(11),col=c("red","green")) > then all ten lines are red, with no warning given. Is there a reason why

Hi If I do this: par(mfrow=c(2,2)) persp(matrix(1:4,6,6),box=F,phi=33,theta=33) persp(matrix(1:4,6,6),box=F,phi=33,theta=33) persp(matrix(1:4,6,6),box=F,phi=33,theta=33) persp(matrix(1:4,6,6),box=F,phi=33,theta=33) ( or indeed layout(matrix(1:4,2,2)) persp . . . . ) then the mesh plots look too small to me. How do I make them larger? -- Robin Hankin Uncertainty Analyst National

How do I draw non-square matrices with image() and get the axes right? Try 1: a <- matrix(rnorm(100),20,5) image(1:20,1:5,a,asp=1,xlab="label here") # No good because the axes don't touch the image Try 2: image(1:20,1:5,a,asp=1,axes=F,xlab="label here") axis(side=1,pos=0) # No good because the x axis label is floating far from the x axis. Try 3:

Hi I have several methods for evaluating a function. The methods are algebraically identical but use different numerical techniques. The different methods work better (converge faster, etc) in different parts of the function's domain. I am compiling a test suite for a package, and would like to verify that the different methods return approximately identical results. Toy example

Hi I have been looking at complex.c and want to access z_cos() and z_sin () from C in one of my packages. There doesn't seem to be a corresponding header file: there is no complex.h file. Where are the prototypes of z_sin() and z_cos() for these functions? grepping didn't help me: find ~/downloads/R-2.1.1/ -name "*.h " | xargs egrep "z_cos"

Hi section 6.1 of R-exts suggests that a package can take over a function in the base package and make it generic. I want to do this with Re() and have the following lines in my R code: "Re" <- function(x){UseMethod("Re" )} "Re.default" <- get("Re" ,pos=NULL,mode="function") "Re.octonion" <- function(x){give.comp(x,1)}