* Push scipy min version to 1.0.0
* Update all ubuntu images to 20.04 focal.
* Add ubuntu images 18.04 bionic and scipy fron conda-forge.
* Fix conditions.
* Pin python 3.6 for ubuntu bionic.
* Change pipeline name.
* Change matrix element name.
* Keep python 3.9 from system not conda in Ubuntu 20.04.
* Remove python directive when unnecessary.
* Cleanup.
* Downgrade to python 3.6 as scipy 1.0.0 is incompatible with 3.8.
* Fix comment.
* Fix comment.
* Pin pytest again as we are forced to use 3.6.
* Move to conda installer for 32bit linux.
* Install miniconda for ubuntu 32bit.
* Install wget for ubuntu 32bit.
* Revert 32bit OS to ubuntu bionic 18.04.
* Install scipy from pip in 32bit system.
* Fix doctest failures.
* Revert example rendering.
* Relax pytest version in ubuntu install.
* Skip failing tests.
* Put comment at the right place.
* Remove python3.6. Ubuntu32 still needs to be adapted.
* Push numpy and scipy min versions for compatibility with 3.7.
* Push matplotlib min version for compatibility with 3.7. Install numpy via pip in 32bit linux.
* Install numpy before scipy in Linux 32bit.
* Pass numpy version to linux32.
* Test 32bit architecture on debian buster (still exists for 32bit with python 3.7).
* Install matplotlib from distribution.
* Syntax error...
* Stick to the numpy debian version to avoid Expected 124 from C header, got 112 from PyObject error.
* Clean comments.
* Revert skip in doctest to check with new dependencies.
* Rename distrib.
* Skip again...
* Fix test on check_array.
* Remove comment and fix lint at the same time.
* Clean import.
* Increase atol in test_derivatives to make the test pass in py37_conda_openblas environment.
* Avoid sparse matrix dependent on scipy version.
* Skip docstring test for pandas versions less then 1.1.0.
* Fix lint error.
* Empty commit to force checks.
* Add minimal dependencies in changelog.
* Update to python 3.7 CircleCI and Travis builds.
* Move to debian buster for python3.7 dependencies.
* Fix the container tag.
* Lower the minimal pandas version for compatibility with python 3.7.
Thomas J. Fan