Changelog =========

Nutils is being actively developed and the API is continuously evolving. The following overview lists user facing changes as well as newly added features in inverse chronological order.

Changes since version 5.0

  • Use stringly for command line parsing.

    Nutils now depends on stringly (version 1.0b1) for parsing of command line arguments. The new implementation of is fully backwards compatible, but the preferred method of annotating function arguments is now as demonstrated in all of the examples.

    For new Nutils installations Stringly will be installed automatically as a dependency. For existing setups it can be installed manually as follows:

    $ python3 -m pip install –user –upgrade stringly

  • Fixed and fallback lengths in (namespace) expressions

    The nutils.function.Namespace has two new arguments: length_<indices> and fallback_length. The former can be used to assign fixed lengths to specific indices in expressions, say index i should have length 2, which is used for verification and resolving undefined lengths. The latter is used to resolve remaining undefined lengths.

    >>> ns = nutils.function.Namespace(length_i=2, fallback_length=3)
    >>> ns.eval_ij('δ_ij') # using length_i
    >>> ns.eval_jk('δ_jk') # using fallback_length
  • Treelog update

    Nutils now depends on treelog version 1.0b5, which brings improved iterators along with other enhancements. For transitional convenience the backwards incompatible changes have been backported in the nutils.log wrapper, which now emits a warning in case the deprecated methods are used. This wrapper is scheduled for deletion prior to the release of version 6.0. To update treelog to the most recent version use:

    python -m pip install -U treelog
  • Unit type

    The new nutils.types.unit allows for the creation of a unit system for easy specification of physical quantities. Used in conjuction with this facilitates specifying units from the command line, as well as providing a warning mechanism against incompatible units.

    >>> U = types.unit.create(m=1, s=1, g=1e-3, N='kg*m/s2', Pa='N/m2')
    >>> def main(length=U('2m'), F=U('5kN')):
    ...   topo, geom = mesh.rectilinear([numpy.linspace(0,length,10)])
    $ python length=25cm # OK
    $ python F=10Pa # error!
  • Sample basis

    Samples now provide a nutils.sample.Sample.basis(): an array that for any point in the sample evaluates to the unit vector corresponding to its index. This new underpinning of nutils.sample.Sample.asfunction() opens the way for sampled arguments, as demonstrated in the last example below:

    >>> H1 = mysample.asfunction(mydata) # mysample.eval(H1) == mydata
    >>> H2 = mysample.basis().dot(mydata) # mysample.eval(H2) == mydata
    >>> ns.Hbasis = mysample.basis()
    >>> H3 = 'Hbasis_n ?d_n' @ ns # mysample.eval(H3, d=mydata) == mydata
  • Higher order gmsh geometries

    Gmsh element support has been extended to include cubic and quartic meshes in 2D and quadratic meshes in 3D, and parsing the msh file is now a cacheable operation. Additionally, tetrahedra now define bezier points at any order.

  • Repository location

    The Nutils repository has moved to For the time being the old address is maintained by Github as an alias, but in the long term you are advised to update your remote as follows:

    git remote set-url origin