SUNDIALS: SUite of Nonlinear and DIfferential/ALgebraic Equation Solvers
IDAS

IDAS is a package for the solution of differential-algebraic equation (DAE) systems in the form F(t,y,y’,p)=0 with sensitivity analysis capabilities (both forward and adjoint modes).

IDAS is a superset of IDA and hence all options available to IDA (with the exception of the FIDA interface module) are also available for IDAS.

Depending on the number of model parameters and the number of functional outputs, one of two sensitivity methods is more appropriate. The forward sensitivity analysis (FSA) method is mostly suitable when the gradients of many outputs (for example the entire solution vector) with respect to relatively few parameters are needed. In this approach, the model is differentiated with respect to each parameter in turn to yield an additional system of the same size as the original one, the result of which is the solution sensitivity. The gradient of any output function depending on the solution can then be directly obtained from these sensitivities by applying the chain rule of differentiation.

The adjoint sensitivity analysis (ASA) method is more practical than the forward approach when the number of parameters is large and the gradients of only few output functionals are needed. In this approach, the solution sensitivities need not be computed explicitly. Instead, for each output functional of interest, an additional system, adjoint to the original one, is formed and solved. The solution of the adjoint system can then be used to evaluate the gradient of the output functional with respect to any set of model parameters.

The FSA module in IDAS offers the choice between a simultaneous corrector method and a staggered corrector method. The ASA module provides the infrastructure required for the backward integration in time of systems of differential-algebraic equations dependent on the solution of the original DAEs. It employs a checkpointing scheme for efficient interpolation of forward solutions during the backward integration.

See Software page for download.

 

idas release history
 

What’s new in v2.0.0?

  • New features and/or enhancements
    • New linear solver API and interfaces for all SUNDIALS packages and linear solvers.  The goal of the redesign of these interfaces was to provide more encapsulation and ease in interfacing custom linear solvers and interoperability with linear solver libraries.
      • Added generic SUNMATRIX module with three provided implementations: dense, banded, and sparse.  These implementations replicate previous SUNDIALS Dls and Sls matrix structures in a single object-oriented API.
      • Added example problems demonstrating use of generic SUNMATRIX modules.
      • Added generic SUNLINEARSOLVER module with eleven provided implementations: dense, banded, LAPACK dense, LAPACK band, KLU, SuperLU_MT, SPGMR, SPBCGS, SPTFQMR, SPFGMR, and PCG.  These implementations replicate previous SUNDIALS generic linear solvers in a single object-oriented API.
      • Added example problems demonstrating use of generic SUNLINEARSOLVER modules.
      • Expanded package-provided direct linear solver (Dls) interfaces and scaled, preconditioned, iterative linear solver (Spils) interfaces to utilize generic SUNMATRIX and SUNLINEARSOLVER objects.
      • Removed package-specific, linear solver-specific, solver modules (e.g. CVDENSE, KINBAND, IDAKLU, ARKSPGMR) since their functionality is entirely replicated by the generic Dls/Spils interfaces and SUNLINEARSOLVER/SUNMATRIX modules.  The exception is CVDIAG, a diagonal approximate Jacobian solver available to CVODE and CVODES.
      • Converted all SUNDIALS example problems to utilize new generic SUNMATRIX and SUNLINEARSOLVER objects, along with updated Dls and Spils linear solver interfaces.
      • Added Spils interface routines to ARKode, CVODE, CVODES, IDA and IDAS to allow specification of a user-provided “JTSetup” routine. This change supports users who wish to set up data structures for the user-provided Jacobian-times-vector (“JTimes”) routine, and where the cost of one JTSetup setup per Newton iteration can be amortized between multiple JTimes calls.
    • Two new NVECTOR modules added: for CUDA and RAJA support for GPU systems.  These vectors are supplied to provide very basic support for running on GPU architectures.  Users are advised that these vectors both move all data to the GPU device upon construction, and speedup will only be realized if the user also conducts the right-hand-side function evaluation on the device. In addition, these vectors assume the problem fits on one GPU. For further information about RAJA, users are referred to the web site, https://software.llnl.gov/RAJA/.
    • Addition of sunindextype option for 32- or 64-bit integer data index types within all SUNDIALS structures.
      • Sunindextype can be int64_t or int32_t or long long int and int depending on machine support for portable types.
      • The Fortran interfaces continue to use long_int for indices, except for their sparse matrix interface that now uses the new sunindextype.
      • Includes interfaces to PETSc, hypre, SuperLU_MT, and KLU with either 64-bit or 32-bit capabilities depending how the user configures SUNDIALS.
    • Temporary vectors were removed from preconditioner setup and solve routines for all packages.  It is assumed that all necessary data for user-provided preconditioner operations will be allocated and stored in user-provided data structures.
    • The file include/sundials_fconfig.h was added.  This file contains SUNDIALS type information for use in Fortran programs. 
    • Added support for many xSDK-compliant build system keys.
      • The xSDK is a movement in scientific software to provide a foundation for the rapid and efficient production of high-quality, sustainable extreme-scale scientific applications. 
      • More information can be found at https://xsdk.info.
    • Added functions SUNDIALSGetVersion and SUNDIALSGetVersionNumber to
      get SUNDIALS release version information at runtime.

    • To avoid potential namespace conflicts, the macros defining booleantype values TRUE and FALSE have been changed to SUNTRUE and SUNFALSE respectively.

    • In build system:
      • Added separate BLAS_ENABLE and BLAS_LIBRARIES CMake variables.
      • Additional error checking during CMake configuration.
      • Fixed minor CMake bugs.
      • Renamed CMake options to enable/disable examples for greater clarity and added option to enable/disable Fortran 77 examples:
        • Changed EXAMPLES_ENABLE to EXAMPLES_ENABLE_C.
        • Changed CXX_ENABLE to EXAMPLES_ENABLE_CXX.
        • Changed F90_ENABLE to EXAMPLES_ENABLE_F90.
        • Added EXAMPLES_ENABLE_F77 option.
    • Corrections and additions to all User Guides.

 

  • Bug fixes
    • Added missing prototype for IDASetMaxBacksIC in ida.h. and idas.h.

 

What’s new in v1.3.0?

  • New features and/or enhancements
    • Two new NVECTOR modules added: for Hypre ParVector and PETSc.
    • In vector API, added new required function, N_VGetVectorID.
    • Upgrades to sparse solver interfaces; now support CSR matrix type with KLU solver.
    • Example codes were changed from using NV_DATA macro to using N_VGetArrayPointer_* when using the native vectors shipped with SUNDIALS.
    • In interpolation routines for backward problems, added logic to bypass sensitivity interpolation if input sensitivity argument is NULL.
    • Changed each **FreeB() to type int; added return(0) to each.  
    • Added optional input function IDASetMaxBacksIC to limit number of linesearch backtrack operations in IDACalcIC.  User guides amended accordingly.
    • Added idasRoberts_FSA_klu.c, idasRoberts_FSA_sps.c, idasRoberts_ASAi_klu.c, and idasRoberts_ASAi_sps.c sensitivity analysis examples using sparse direct solvers.  Also added idasFoodWeb_bnd_omp.c and idasFoobWeb_kry_omp.c OpenMp examples.
    • Minor corrections and additions to User Guide, including removal of references to specific NVECTOR names in usage skeletons.
    • Updated to return integers from linear solver and preconditioner ‘free’ functions.
  • Bug fixes
    • Fixed memory leak in banded preconditioner interface.
    • Fixed some examples w.r.t. switch to new macro/function names SUNRexp etc.
    • Various minor fixes to installation-related files.
    • Corrected name N_VCloneEmptyVectorArray to N_VCloneVectorArrayEmpty in all documentation files.

What’s new in v1.2.0?

  • New features
    • Added interface to the sparse direct solver KLU.
    • Added interface to SuperLU_MT.
  • Bug fixes
    • Fixed minor bug in IDARootfind involving rootdir input.
    • Fixed line setting smu in IDALapackBand.
  • Changes to user interface
    • Added user Jacobian option functions IDADlsSetDenseJacFnBS and IDADlsSetBandJacFnBS.
  • Changes to documentation
    • Added paragraphs on IDAAdjReInit and IDAGetAdjY.
  • Changes related to the build system
    • Dropped support and documentation of the Autotools mode of installation.

What’s new in v1.1.0?

  • Bug fixes
    • fixed major logic errors in integration of backward problems.
    • linear solver memory set to zero after being created.
    • linear solver memory is freed on an error return.
    • memory leak fixed in two IDASp***Free functions.
    • added missing vector pointer setting in IDASensLineSrch.
    • in IDACompleteStep, fixed conditionals on loading divided difference arrays for a possible order increase.
  • Changes to user interface
    • Problem size and related integers (bandwidth parameters etc.) all have type long int, except for those in user calls specifying BLAS/LAPACK routines.
    • index ‘which’ changed from type long int to int.

What’s new in v1.0.0?

  • Initial release.