[petsc-users] Two questions regarding SNESLinesearchPrecheck

[David Knezevic]

We're using SNESLinesearchPrecheck in order to implement some nonlinear
continuation methods, and we had a couple of questions:

1. The "search direction" that is handed to the pre-check function is
referred to as "y" in the documentation. We had assumed that we would have
"y = delta_x_k", where delta_x_k is as shown in the attached screenshot
from the PETSc manual. But after doing some testing it seems that in fact
we have "y = -delta_x_k", i.e. y is the NEGATIVE of the Newton step. Is
this correct?

2. In the documentation for SNESLineSearchPreCheck it says that "x" is the
"current solution". Referring again to the attached screenshot, does this
mean that it's x_k+1 or x_k? I assume it means x_k+1 but I wanted to
confirm this.

Thanks for your help!

Regards,
David
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