.. _releasenotes-31:

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Version 3.1 (2003/04/04)
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**New iterative methods**

- Optimization:

  - NPSOL v5.0 update.
  - OPT++ method consolidation (from 15 down to 6) and additional constraint coverage (added BCFDNewton and GNewton NIPS).
  - Initial rSQP++/MOOCHO interface (large-scale optimization).
  - Initial COLINY interface for access to APPS and DIRECT optimizers.

- Uncertainty quantification:
  
  - New f90 LHS library (not yet publicly available).

    - restricted pairing: enforces the desired correlation in the sample set, whether inducing a user-specified correlation or minimizing correlation for the default uncorrelated case.
    - bounded normal and bounded lognormal distributions
    - bin-based and point-based histogram distributions
    - additional output: sample histograms and achieved correlation in f90 output, coefficient of variation and confidence interval statistics in DAKOTA output.
    - consolidation of old/new sampling for LHS/PCE
	
  - MV/AMV/AMV+/FORM reorganization.
  
- Parameter estimation:

  - New NLSSOL SQP-based generally-constrained nonlinear least squares.
  - New least squares iterator branch to support NLSSOL and OPT++ GNewton.
    
- Sensitivity/statistical analysis:

  - Distribution of DDACE under LGPL.
  - Consolidation of function evaluation management routines among design of experiments, UQ sampling, and parameter studies.

**New strategies**

- Surrogate-based optimization

  - Enhancements to penalty function consistency.
  - Enhancements to trust region management and convergence controls.
  - New 1st-order additive correction (thanks to Natalia Alexandrov and Michael Lewis for formulation). Improves convergence in SBO test cases employing hierarchical surrogates.

- Optimization under uncertainty (OUU)

  - New trust-region surrogate-based OUU (paper).
  - Enhanced data flow in Layered/Nested models.

- Concurrent (Pareto set, Multi-start)

  - New random starts capability (in place of or in combination with user-specified starts).
  - New results/timing summaries.
  - Parallel scheduling enhancements.

**New DAKOTA facilities**

- New library mode:

  - Library creation (libdakota.a et al.) and consolidation in Dakota/lib.
  - New API for cases when command line arguments are not directly accessible.
  - Access to final strategy results.
  - Library mode documentation.

- New surrogates:

  - Linear and cubic polynomials to supplement existing quadratic polynomial.
  
- Enhanced random seed control for multiple sampling sets in DDACE and LHS

  - 4 seed selections: combinations of fixed vs. sequenced and user-specified vs. system-generated.
  - Sequenced seeds result in variable sampling patterns which enhance reliability and accelerate convergence in SBO, OUU, and SBOUU.

- New error checking in approximation classes, uncertain variables, PCE, submodel compatibility, and method constraint support.
- Efficiency enhancements:

  - Dropped pre-ANSI C++ mode which allowed for STL streamlining and optimization.
  - Additional output control: debug/verbose/normal/quiet/silent settings, -i/-o/-e command line options.
  - Evaluation cache and restart deactivation option.
  - New MPI intra-communicators to streamline message broadcasts for large parallel runs.
  - Streamlined communicator repartitioning in strategies.
  
- New utilities:

  - Restart repair by evaluation id.
  - 3D graphics fonts (PLplot) distributed with executables.
  
- SQA:
  - Automated DAKOTA testing: nightly build verifications, new regression test facilities employing test matrices, unit testing under development.
  - Nightly library testing for SGOPT, PICO, and UTILIB (OPT++, DDACE to follow).
  - Requirements/issue tracking (Bugzilla, restricted access), design tracking, release management (automated posting of nightly builds available shortly).

**Contributions from the user community**

- Distributed testing/issue identification:

  - SGOPT: problem size limitations removed (identified by Michel Beaulieu), real-valued GA bound constraint bug resolved (identified by Hongman Kim), multi_step keyword mismatch resolved (identified by Don Flaggs).
  - OPT++: bound constraints fixed in PDS (identified by Don Flaggs), final solution returned properly (identified by Michel Beaulieu).
  - DOT/CONMIN: registration of automatic method switches for consistency in output headers (identified by Don Flaggs).
  - SBO fraction of cauchy decrease bug resolved (identified by Myles Baker).
  - LINUX graphics configuration generalized (identified by Constantine Orogo).
  - IBM POE: replaced short hand checks for MPI_REQUEST_NULL (identified by Scott Brandon).
  - DEC asynchronous evaluations: activated usleep() function in asynch schedulers as OSF 5.1 is now supporting it (identified by Scott Brandon).
  
- Enhancement suggestions:

  - Surrogate builds from files (requested by Srinivas Kodiyalam)
  - Output of surrogate functional forms (requested by Srinivas Kodiyalam).
  - Seed output from SGOPT to allow run recreation (requested by Don Flaggs).
  - Response function descriptors (requested by Hongman Kim).

- Contributed code:

  - Cygwin evaluation and initial port (contributed by Hongman Kim).
  - Mac OSX evaluation (contributed by Carl Hagelberg).
  - Linear polynomial surrogate model (contributed by Myles Baker).
  - Direct interface to Phoenix Integration's ModelCenter and merged variable descriptors (contributed by Hongman Kim).