Changes in version 0.9.6 (2026-04-22)                  

MC_IS estimator correction and reliability analysis improvements

Monte Carlo Importance Sampling (MC_IS)

  - Corrected the MC_IS estimator to remove bias caused by the previous
    self-normalized implementation.
  - Refactored worker aggregation in MC_IS_single to ensure correct
    accumulation of weighted samples and consistent global statistics.
  - Workers now compute weights directly and return aggregated
    statistics instead of raw sample vectors.

System reliability analysis

  - Fixed incorrect propagation of sys_type from
    calculateSystemProbability() to MC_IS_system(), ensuring that serial
    and parallel systems are evaluated correctly.
  - Resolved cases of uninitialized variables in the system worker
    (mode_ids, shift, and references to I_matrix).
  - Enabled multimodal sampling for both serial and parallel systems.

Performance improvements

  - Optimized the transformation from u-space to x-space by removing
    large intermediate matrices and computing quantiles column-wise.
  - Replaced large failure indicator matrices with incremental counters
    to significantly reduce memory usage.
  - Reduced worker-to-master communication in parallel runs by returning
    only aggregated statistics.

Validation and testing

  - Added regression tests for MC_IS_single, including linear
    limit-state cases, non-normal distributions, and rare-event
    scenarios.
  - Added system reliability tests comparing results with MC_CRUDE.
  - Verified consistency with FORM results within expected Monte Carlo
    error.

                 Changes in version 0.9.5 (2026-03-24)                  

Major refactoring of object classes

System and reliability objects

  - Reworked all reference classes (SYS_PROB, SYS_PARAM, SYS_LSF,
    PROB_BASEVAR, …).
  - Introduced explicit constructors with argument validation for better
    error handling.
  - Improved consistency between mean, standard deviation and
    coefficient of variation.
  - Added robust forward/backward transformations for all supported
    distributions.
  - Fixed handling of zero mean values (Cov <- Inf) to reflect infinite
    relative scatter.

Limit-state functions

  - Field type for func changed from "function" to "ANY" with explicit
    default NULL. This prevents creation of dummy closures and allows
    proper missing-function detection.
  - Enhanced $check() method:
      - Distinguishes between missing, empty, and valid limit-state
        functions.
      - Provides informative error messages used by automated tests.

Parametric study objects

  - Constructor of SYS_PARAM now correctly forwards arguments to parent
    class (callSuper(...)) ensuring that inherited fields like sys_input
    are preserved.
  - Parallel execution restructured using the global future plan set in
    .onLoad(). The outer level is capped by environment variable
    TesiproV.max_workers (default: 4 cores) while inner Monte-Carlo
    methods manage their own threads.

Probabilistic base variables

  - Complete rewrite of transformation logic in $prepare():
      - Supports normal, lognormal, Gumbel, gamma, beta and Weibull
        distributions consistently.
      - Corrected implementation of the Gumbel distribution
        (location parameter now properly computed as
        location = Mean + digamma(1) * scale; scale derived via (Sd *
        sqrt(6)) / π).
      - Added numerical root search for Weibull shape parameter when
        empirical formula fails.
      - Added empirical, shifted lognormal, Student-t and logStudent-t
        distribution.
  - Distribution caching via digest hash implemented in $getlDistr() for
    performance improvement.

Package infrastructure

  - Added internal .onLoad() function for package-specific default
    options that can later be used by TesiproV functions to configure
    parallel execution in a controlled and CRAN-compliant way.

Minor improvements

  - Better formatted output in $printResults().
  - Consistent English comments throughout codebase for clarity and
    documentation generation via roxygen2.
  - Updated examples in help pages to match new constructors and usage
    patterns.

Compatibility notes

Existing scripts using older class definitions should continue to work
after minor adjustments: replace direct field assignments by constructor
arguments where applicable, and ensure that limit-state functions are
defined before calling $check().

                       Changes in version 0.9.2.0                       

Better implementation of parallel computing in Unix and macOS
environments.
Changed RNG handling in parallel approach.

                       Changes in version 0.9.1.0                       

  - First release.

© 2021–2026 K. Nille-Hauf, T. Feiri, M. Ricker, T. Lux -- Hochschule
Biberach (until 2022), TU Dortmund University – Chair of Structural
Concrete (since 2023)