Also update CI to install qsymm on relevant platforms, and update
pytest config to skip kwant.qsymm tests when qsymm is not installed

Tómas authored 6 years ago and Joseph Weston committed 6 years ago

Co-authored-by: Daniel Varjas <dvarjas@gmail.com>

add magnetic gauge fixing for infinite systems and systems with leads

See merge request kwant/kwant!267
Closes #246.

Test that the sign convention and units are correct, and that
we correctly recover current flowing along the boundaries of
a bar system when a magnetic field is applied.

Magnetic fields are now expressed in units of magnetic flux quantum
per unit area.

We still refer to these as "phases" everywhere in the code.
Working with phase factors means that users do not have to
exponentiate anything (and potentially get an incorrect sign).
In addition this is closer to what we need for non-abelian
gauge fields.

This means less repeated documentation.

Co-authored-by: Pablo Piskunow <pablo.perez.piskunow@gmail.com>
Co-authored-by: Daniel Varjas <dvarjas@gmail.com>

The UI will show the test failures as warnings (which we can
address).

Add first and second derivative calculation to kwant.physics.Bands,
and allow eigenvectors to be optionally returned.

See merge request kwant/kwant!262

The 'out' parameter is only used when you don't want numpy to
allocate a new array for the result, which is not the case here.

Thomas Kloss authored 6 years ago and Joseph Weston committed 6 years ago

np.linalg.eigvalsh returns eigenvalues already in ascending order

There is nothing that consumes lead_paddings right now, but it will be useful
for plotting and gauge fixing.
Closes #266.

Closes #232.
We can further improve on this behavior if we provide a useful class of
callables that can efficiently represent itself in printed form, however this
change is an immediate improvement of plot quality.

maint: clear up warnings in tests

See merge request kwant/kwant!270

This silences a deprecation warning on scipy < 1.2 and numpy > 1.15.

add automatic Peierls phase calculation

Closes #19

See merge request kwant/kwant!219

Co-authored-by: Pablo Piskunow <pablo.perez.piskunow@gmail.com>
Co-authored-by: Daniel Varjas <dvarjas@gmail.com>