Looks like a fatally flawed change I should never have made. I have an MR to revert it https://gitlab.com/petsc/petsc/-/merge_requests/6620 Should get into release and main by tommorow.
Barry > On Jun 19, 2023, at 4:37 PM, Barry Smith <bsm...@petsc.dev> wrote: > > > Sorry about this, we'll take a look and get back to you. > > > >> On Jun 19, 2023, at 4:05 PM, Nabil Abboud via petsc-dev >> <petsc-dev@mcs.anl.gov> wrote: >> >> Dear all, >> >> We were trying to update the petsc version we use in our code to the version >> 3.19.1 when we noticed that some of the unit tests in our code started >> failing. The reason for the failure seems to be due to a change in the >> linesearch logic of petsc version 3.19.1. In particular, the implementation >> of the function SNESLineSearchGetTolerances was modified such that maxstep >> is now scaled with fnorm as shown in the following link >> https://gitlab.com/petsc/petsc/-/blob/main/src/snes/linesearch/interface/linesearch.c#L1097 >> This change seems to be inconsistent with the way maxstep is being used >> later on to compute a step size using the l2 line search algorithm, for >> instance, check the following code >> https://gitlab.com/petsc/petsc/-/blob/main/src/snes/linesearch/impls/l2/linesearchl2.c#L119 >> where maxstep is compared to lambda_update and where maxstep is scaled by >> fnorm whereas lambda_update seems to be a scalar of a different order as >> computed here >> https://gitlab.com/petsc/petsc/-/blob/main/src/snes/linesearch/impls/l2/linesearchl2.c#L111 >> . >> The way this change is reflected in our code is that we were trying to >> enforce a range for the step size provided by the l2 line search between 0.1 >> and 1 and now with the new changes in petsc version 3.19.1 the upper limit >> seems not to hold anymore and we are seeing step sizes larger than 1. >> >> Thank you in advance for your help. >> Best regards, >> Nabil >
