rtol
The relative convergence tolerance.
Declaration
var rtol: DoubleDiscussion
‖ b-Ax ‖₂ < * ‖ b-Ax₀ ‖₂ + atol indicates convergence.
If rtol is equal to 0, the operation uses the default value of sqrt(epsilon).
If it’s negative, the operation treats rtol as 0.0 (it doesn’t use the default).