R help - Nov 2005 - Real FFT

The book "Numerical Recipes in Fortran77" by Press, Teukolsky,
Vetterling and Flannery describes a way to "pack" the even and odd
coordinates of a real vector "R" into a complex vector "C"
of half the length.  Then using various FFT symmetries, they extract the FFT of
"R" from the FFT of "C" which is half the length of
"R",

There is also an inverse process.  

Is there an R function that does this?

Glenn Meyers
ggmeyers@optonline.net

gmeyers@iso.com


	[[alternative HTML version deleted]]

How about 'fft' function. It is a little higher level than Fortran
function
you mention, since array can be any length and you do not need to pack
complex numbers into a vector of floats.

Jarek Tuszynski

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Glenn Meyers
Sent: Wednesday, November 02, 2005 9:50 PM
To: r-help at stat.math.ethz.ch
Subject: [R] Real FFT


The book "Numerical Recipes in Fortran77" by Press, Teukolsky,
Vetterling
and Flannery describes a way to "pack" the even and odd coordinates of
a
real vector "R" into a complex vector "C" of half the
length.  Then using
various FFT symmetries, they extract the FFT of "R" from the FFT of
"C"
which is half the length of "R",

There is also an inverse process.  

Is there an R function that does this?

Glenn Meyers
ggmeyers at optonline.net

gmeyers at iso.com


	[[alternative HTML version deleted]]

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html