Version History for the Pseudospectra GUI

• Version 1.3r2 6th March 2002

  • New `Demos' menu added with many built-in pseudospectra
  • Added ability to plot pseudomodes and eigenmodes
  • Added abililty to plot field of values
  • Restructured help to MATLAB standard
  • Restructured psagui directory to hide internal routines
  • Fixed bug when pseudospectra cancelled, and then zooming performed
  • Go/Stop buttons merged
  • Print Plot moved to menu
  • Added ability to do a print plot over an existing figure
  • Show dimension made default
  • Eigenvalue condition number code improved to use SVD if inverse iteration fails

• Version 1.3r1 28th August 2001

  • Ability to compute pseudospectra of rectangular matrices
  • Addition of zoom out from the initial pseudospectra
  • Addition of isreal flag for rect Hessenberg matrices
  • Axes are now not cleared until the new pseudospectra is ready
  • Change default axis limits to reflect aspect ratio of spectrum
  • Removed psagui.mat file
  • Included psagui_prefs.mat
  • Print plots now appear in correct figure number
  • Provide menu option to allow the use of non-log-spaced epsilon levels
  • Print plots can now be superimposed on existing plots
  • Added `Display Grid' option
  • Added `Display matrix dimensions' option
  • Improved efficiency of projection code (doesn't project if axes unchanged)

• Version 1.2r3 20th June 2001

  • Added 'Estimated remaing time' feature
  • Fixed bug with psacore and psacore_hqr which could cause erroneous results for small matrices
  • Fixed problem with changing levels in text boxes if the step size didn't fit the ends (e.g. -7:2:2 gave [-7 -5 -3])
  • Set current axes in the printable plot to the main ones (allows use of title, grid etc.)
  • Increase default gridsize to 24
  • New `axis-tidy' to reduce unsightly decimal places on axis limits and force x-axis symmetry in some cases for real matrices
  • Update stopping code to improve responsiveness
  • Added new argument to psa which allows you to select a figure number for the GUI, and update an existing figure (which can save on GUI startup time)
  • Added new option opts.ews to allow the input of eigenvalues for rectangular Hessenberg and sparse matrices (if known)

• Version 1.2r2 1st May 2001

  • Included file hessqr.m omitted in previous release (only needed for non-mex-file versions)

• Version 1.2r1, 24th April 2001

  • New mex-files introduced for the core pseudospectra computation leading to speedups of a factor of up to 10 for small matrices (dimension of the order of 100) and a factor of 2 for large matrices (dimension of the order of 1000).
  • Added check to avoid doing initial Schur decomposition if matrix is already upper triangular
  • Added opts.isreal option for use when supplying a matrix already in Schur form
  • Changed default epsilon levels so that instead of a maximum of 14 levels being displayed (starting from the smallest value of epsilon) the correct spread is now displayed with a larger increment
  • A few other minor speedups

• Version 1.1r5, 26th March 2001

  • Fixed a bug which caused slowdown when computing exact pseudospectra of sparse matrices

• Version 1.1r4, 12th January 2001

  • Fixed a bug in eigenvalue condition number routine

• Version 1.1r3, 12th December 2000

  • Exact computation of pseudospectra of sparse matrices broken in previous release

• Version 1.1r2, 11th December 2000

  • Release for MATLAB version 6
  • Connection to eigs for pseudospectra of large matrices (see Using the GUI with sparse matrices)
  • Direct pseudospectra computation for sparse matrices
  • Improved implementation; up to 10% speedup compared to version 1.0
  • Computation of eigenvalue condition numbers
  • Scope for creating .mat files which can be used to easily re-create plots for printing
  • Many minor bug fixes and enhancements

• Version 1.0, 27th June 2000

  • Original release. No support for sparse matrices

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