Starting with the Third Edition of Numerical Recipes, we have two kinds of licenses: personal, non-transferable single-user licenses, and institutional (site) subscriptions. The difference between these two kinds of license is explained here (http://www.nr.com/licenses).

Institutional subscriptions include both electronic access to the complete Numerical Recipes Third Edition book, and also access to, and a license to use, the Numerical Recipes code. See complete license terms here (http://www.nr.com/aboutNR3license.html), and learn how to subscribe here (http://www.nr.com/aboutNR3electronic.html).

Personal licenses can be used on any number of computers, but only by one individual person. Personal licenses do not include access to the electronic version of the book, since that is sold separately by individual subscription valid on up to three machines.

Naturally, we will continue to honor licenses for previous editions, including perpetual site licenses, that were purchased under our previous licensing system. All the queries below that are dated before 1 September, 2007, refer to the previous licensing system.

Dear Bill,

I purchased the Numerical Recipes
for Fortran 77 back in May 1995, which
was ver. 2.06 at that time. When I
installed it on my home PC, it mentioned
that the installation license was for
a single PC installation. What I was
wondering is now that I have a work laptop
9 years later, is it okay as a single user
to legally install the Recipes routines
on two different machines, neither of
which will be used simultaneously and
also with me as the single user?

Thanks for your time,
Bob Wolfgang :)

Bob,

This is a very pertinent question.

Your Numerical Recipes license is actually a "Single-Screen" license, and covers the use of the software on a single physical screen. In most cases, the screen and the CPU are part of the same workstation, and they are used by a single person,
so the distinctions between a "single-screen", a "single-computer" and a "single-user" license are not relevant.

However, in the present case the distinction is important. It would not be within the terms of the single-screen license to install the software on two machines for use on two different screens. It would, however, be okay to transfer the software to a newer computer and remove it from the old one, so that the use of it was still on a single screen.

[Added 9/28/2007:] Starting with the Numerical Recipes Third Edition, this issue no longer arises, because our personal, single-user licenses now allow unlimited use by a single individual on any number of computers.

Bill Vetterling
Numerical Recipes Software