v0.17.2

New Features

• Adds desc.objectives.DeflationOperator, a new objective class which can be used to apply deflation techniques to equilibrium and optimization problems to find multiple local minima or multiple solutions from a single initial point, either by wrapping an existing desc.objectives._Objective object or by including as an additional penalty or constraint. Also adds a tutorial showing this functionality.
• Sub-objectives of an ObjectiveFunction can now have different use_jit values than the ObjectiveFunction. These objectives have to be built before building the ObjectiveFunction.
• Adds num_neighbors parameter to CoilSetMinDistance that limits the pairwise distance computation to the nearest neighbors per coil, reducing memory useage for large coilsets.
• Method to plot frequency spectrum of inverse stream map in field line coordinates Bounce2D.plot_angle_spectrum.
• Method to compute bounce integrals in batches is now added to the public API Bounce2D.batch.
• Initiated deprecation of Bounce2D.compute_fieldline_length in favor of eq.compute("V_psi").
• The quadrature resolution in Bounce2D.compute_fieldline_length now corresponds to the resolution over a single field period instead of the resolution over a toroidal transit.
• Adds an optional attribute ion_density to the Equilibrium class, to allow the ion density profile to be set independently of the electron density and effective atomic number. Also adds compute functions for "ni_rr" and "Zeff_rr".
• Modernizes dependencies to use nvidia-ml-py in place of nvgpu.

Important

If you are updating an existing software environment uninstall pynvml first and then reinstall the dependencies to correctly get nvidia-ml-py.

Bug Fixes

• Fixes SyntaxError thrown when loading hdf5 data from file-like objects.
• Fixes a bug in OmnigenousField.change_resolution when changing L_B.
• Scaling a ScaledProfile or taking power of a PowerProfile now only updates the scale/power attributes instead of nesting the ScaledProfile/PowerProfiles.
• jax.Arrays in _static_attrs will be automatically converted to np.ndarray to prevent stalling code. In general, jax arrays should be omitted in _static_attrs.
• Fixes a bug in desc.magnetic_fields.fieldline_integrate when calling with an integer bs_chunk_size.

Performance Improvements

• Reduces import time of desc modules.
  • Now, desc.compute._build_data_index uses depth-first search algorithm to construct the dependency tree.
  • Some of the default value computations at import time are removed (i.e. desc.integrals.bounce_integral.default_quad)
• Significantly improves convergence of inverse stream maps (#1919).
• Check-pointing to bounce integrals to improve speed and reduce memory of reverse mode differentiation.
• Resolves a JAX memory regression in bounce integrals by avoiding materialization of a large tensor in memory. Previously, we had closed the issue by adding nuffts as a workaround. This update actually solves the issue for the case when a user specifies to not use nuffts as well.
• ObjectiveFunction.print_value can now use the previously computed compute_scaled_error values to print. For bounded objectives, we fall back to computing compute_unscaled. Additionally, compute_scaled_error and array splitting are used in other parts of the code to prevent recompilation for one-time tasks, which makes initialization faster.

Deprecations

• constants argument of compute, jvp, jac, grad and hess methods (including all of their variants) to all objective classes (including ObjectiveFunction and wrappers) is deprecated and will be removed in a future release. This argument was not necessary, and the code will still work if user doesn't pass it. Users should update their custom objectives for this change. In addition, constants property of the ObjectiveFunction and all sub-classes of _Objective is deprecated.

New Contributors

• @andycthea made their first contribution in #2123
• @TElder-thea made their first contribution in #2140
• @matthewfeickert made their first contribution in #2163

Full Changelog: v0.17.1...v0.17.2