README file for INSTAB Version 1.0

NAME
     INSTAB - automatic detection of instability in numerical algorithms

DESCRIPTION
     INSTAB is a software package for automatically detecting
     instability in numerical algorithms. INSTAB implements functional
     stability analysis, which uses the relationship between the
     forward error, the backward error, and a problem's condition to define
     a function that estimates a lower bound on the backward error. The
     subplex optimization method then maximizes the function. A numerical
     algorithm is unstable if the maximization shows that the backward
     error can become large. Since numerical algorithms are treated as
     black boxes, INSTAB normally requires little more than an executable
     version of a numerical algorithm to determine if it is unstable.

INSTALLATION
     Edit the Makefile as necessary and type:

	 make  

     This will create a linkable library named instab.a and a
     demonstration executable named instabtest.

EXAMPLE
     To test the stability of Gaussian Elimination without pivoting on
     4x4 systems type:

	instabtest < instabtest.in > instabtest.out

     The output shows the estimated backward error for each search for 
     instability.  A large backward error means that the algorithm is 
     unstable. Search the output for "UNSTABLE" to see the most extreme 
     examples of instability.

     To test other algorithms, edit the interface routines APPROX
     and EXACT in instabtest.f as necessary.

AUTHOR
     Tom Rowan <na.rowan@na-net.ornl.gov>
