[python-control-announce] Slycot 0.3.4 released

[Rory Y. <ror...@gm...>]

Slycot 0.3.4 has been released on Github [1], uploaded to PyPI, and should be available from conda shortly, via the conda-forge channel [2].  Thanks to everyone who contributed!

[1] https://github.com/python-control/Slycot/releases/tag/v0.3.4
[2] `conda install -c conda-forge slycot`

# New features

Support for four SLICOT routines was added by Marcus Liljedahl.

## ag08bd Process system pencil to find multivariable zeros

ag08bd takes a system pencil (E,A,B,C,D) and returns a matrix pair (Af, Ef) which can be used to find the finite multivariable ("Smith") zeros.  The orders of infinite zeros, right and left Kronecker indices, and multiplicities of infinite eigenvalues are also returned.

## sb10jd Convert descriptor to non-descriptor form

sb10jd converts a descriptor state-space system (E,A,B,C,D) to a regular state-space system (Ad, Bd, Cd, Dd).

## tg01ad Balance system pencil

tg01ad balances system pencils (E,A,B,C,D), with D=0, such that the rows and columns of the resulting pencil are as close in norm as possible.

## tg01fd SVD-like coordinate form of system pencil

tg01fd finds the orthogonal transformation matrices for a system pencil (E,A,B,C,D), with D=0, such that the result is in SVD-like coordinate form.

# Build

Rene van Paassen switched the build over to scikit-build, which allows for flang to be used to build SLICOT on Windows, and improves the build output for developers.

# Testing

Python 3.7 was added to the Travis CI build set.

The tests no longer use the deprecated np.matrix type.

Added a regression test for #6, for td04ad.

# Pull requests and issues associated with the release

(numbers refer to Github issues and PRs).

PRs merged: #32, #34, #36, #38, #43, #45, #51, #52, #53, #56, #57
Issues fixed: #35, #37, #47, #55
Issues closed ("wont-fix"): #40, #41, #48