diff --git a/tutorials/introduction-to-linear-operators/index.md b/tutorials/introduction-to-linear-operators/index.md index bfdfd3f6..aad0bcfc 100644 --- a/tutorials/introduction-to-linear-operators/index.md +++ b/tutorials/introduction-to-linear-operators/index.md @@ -326,7 +326,7 @@ norm(b - opAAT * x) ## Limited memory BFGS and SR1 -Two other useful operators are the Limited-Memory BFGS in forward and inverse form. +Another useful operator is the Limited-Memory BFGS in forward and inverse form. ```julia B = LBFGSOperator(20) @@ -351,7 +351,10 @@ r -There is also a LSR1 operator that behaves similarly to these two. +There is also a Limited-Memory SR1 operator for which only the forward form is implemented. +Note that the SR1 operator can be indefinite; therefore, its inverse form is less relevant than for the BFGS approximation. +For this reason, the inverse form is not implemented for the SR1 operator. + ## Restriction, extension and slices