v0.4.2

PSDMatrices v0.4.2

Diff since v0.4.1

Closed issues:

• Should choleskify return Cholesky type? (#20)

Merged pull requests:

• choleskify vs triangularize (#24) (@pnkraemer)
• removed todense() (#25) (@pnkraemer)
• Implement LinearAlgebra.diag (#26) (@nathanaelbosch)