[petsc-users] Natural norm

[De Groof, Vincent Frans Maria]

Hi all,


the natural norm for positive definite systems in Petsc uses the preconditioner B, and is defined by r' * B * r. Am I right assuming that this way we want to obtain an estimate for r' * K^-1 * r, which is impossible since we don't have K^-1? But we do know B which is approximately K^-1.


I'm sorry for this, I guess, basic question, but I just wanted to be sure.


kind regards,
Vincent
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