MAINT: stricter linalg argument checking
PEP8: pep8
MAINT: exclude masked arrays from linalg functions
DOC: more verbose error message
WIP: avoid densifying on sparse elementwise mult
ENH: Add Wishart and inverse Wishart distributions
DOC: Add  to stats docs.
MAINT: pep8 compliance.
TST: assert_equal -> assert_allclose
DOC: Emphasize positive definite / fix typos.
REF: Minor computational / style changes
- log(prod(…)) -> sum(log(…))
- two variable name improvements
- np.dot(x.T, x) -> np.outer(x,x)
FIX: Two bugs in rvs()
ENH: Improve inverse Wishart performance: pdf, rvs
ENH: Univariate inv-Wishart performance: pdf, rvs
FIX: Fix implementation of Wishart rvs()
REF: Style improvements.
TST: Add rvs tests
- Kolmogorov–Smirnov test against chi2, invgamma
- Comparison against manual RVS creation
ENH: More efficient inverse Wishart rvs.
ENH: specific warning if matlab file is empty

Give a more specific and informative error when the matlab file is
empty.  Closes gh-4081
ENH: linalg: Add a function to compute the inverse of a Pascal matrix.