[R] .fortran code

[Ravi Varadhan]

If you look at the source code for eigen() you will notice that the .Fortran
calls a subroutine named either "rs.f" or "rg.f" depending on whether your
matrix is real and symmetric or real and asymmetric, respectively.  So, you
can look at these files if you had installed the source code.  Even if you
had not installed the full source, you can google using keywrods "rs.f
eigenvalue" or "rg.f eigenvalue" to see the Fortran code for these functions
available from EISPACK.  However, I am not sure how illuminating that would
be since rs.f and rg.f are just calling routines that each calls a number of
other subroutines.  So, unless you are willing to spend a great deal of
time, you may not be any wiser at the end of all this.

Ravi.

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Ravi Varadhan, Ph.D.

Assistant Professor, The Center on Aging and Health

Division of Geriatric Medicine and Gerontology 

Johns Hopkins University

Ph: (410) 502-2619

Fax: (410) 614-9625

Email: rvaradhan at jhmi.edu

Webpage:  http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html

 

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-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of Shubha Vishwanath Karanth
Sent: Thursday, February 07, 2008 9:42 AM
To: r-help at stat.math.ethz.ch
Subject: [R] .fortran code

Hi,

 

I need to look/understand what the ".fortran()" doing in say, the source
code of the "eigen" command. How do I look into this?

 

Thanks,

Shubha

 

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