Here is a gap. What if A is real-symmetric but not posdef. What algorithm would the built-in solver A\b resort to? And I know there is an idea to convert it to posdef:
- left precondition: we solve (A^\top A) x =A^\top b
- right precondition: we solve (AA^\top)y = b, then x := A^\top y
would these methods be competent? Allegedly the condition number is squared.
PS I want to look into the multiple dispatch of LinearAlgebra.jl, thus I need a tool like Debugger.jl, but I don’t know where is wrong currently → ERROR: Debugger.jl requires a LineEditREPL type of REPL. 