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What is shasta?
Mount Shasta is a 4317--meter somewhat active volcano in Northern California.
Its snow--capped multiple--crater summit, pictured above, is a well-known
california landmark as well as a ski resort. This page describes however
shasta, an interactive interface to the
library that provides some efficient computations revolving around operators
and systems in
Q[n,E] or Q(n)[E] where E is the
shift operator that sends n to n+1. In fact, the main goal
of shasta is to provide access to selected functionalities of the
Sum^it library to other computer algebra systems, or to users who
do not own an Aldor compiler, or who feel more confortable with interactive
access to a library. The functionalities currently provided by shasta are
the ones that tend to be missing from several commercial computer algebra
If you do not need any of the above computations, then you probably will
not have much use for shasta. Otherwise, since shasta provides implementations
of several recent algorithms for those computations, it is worth giving
it a try.
Basic arithmetic in Q[n,E], including adjoints and left and
right gcd's and lcm's.
Rational kernels, i.e. Ker(L) /\ Q(n)
and rational solutions of inhomogeneous equations of the form
L(y) = g.
Rational kernels of systems of the form Y(n+1) = A(n) Y(n).
Hypergeometric solutions, i.e. the solutions y of L y = 0
such that y(n+1)/y(n) is in Q(n).
Factorisation and decomposition of second and third-order operators.
What is the current version?
The current distributed version is 1.0.0, released September 4, 2002.
How do I get shasta?
You must download first the platform-independent part by clicking
then download the executable for the operating system(s) and platform(s)
How do I install shasta?
Issue tar -xvzf shasta.tar.gz
to install the platform-independent parts.
The executables can be installed anywhere.
More installation details are in the
file and in the
Are there other Sum^it servers?
Yes, if you are interested in linear ordinary differential equations,
you can take a look at the
Bernina server, that provides similar functionalities for those equations.
Last update: 28 October 2002