<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">That seems to to allow for me to cook up a convergence test in terms of the 2 norm. What I’m really looking for is the ability to change things to be something like the 2 norm of the vector with elements<div class=""><br class=""></div><div class="">F_i/|x_i|</div><div class=""><br class=""></div><div class="">where I am looking for a root of F(x). I can just build that scaling into the form function, but is there a way to do it without rewriting that piece of the code?</div><div class=""><br class=""></div><div class=""><div class=""><div class=""><br class=""><div class="">
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; ">-gideon</span>
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<br class=""><div><blockquote type="cite" class=""><div class="">On Jan 12, 2016, at 12:14 AM, Barry Smith <<a href="mailto:bsmith@mcs.anl.gov" class="">bsmith@mcs.anl.gov</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class=""><br class=""> You can use SNESSetConvergenceTest() to use whatever test you want to decide on convergence.<br class=""><br class="">Barry<br class=""><br class=""><blockquote type="cite" class="">On Jan 11, 2016, at 3:26 PM, Gideon Simpson <<a href="mailto:gideon.simpson@gmail.com" class="">gideon.simpson@gmail.com</a>> wrote:<br class=""><br class="">I’m solving nonlinear problem for a complex valued function which is decomposed into real and imaginary parts, Q = u + i v. What I’m finding is that where |Q| is small, the numerical phase errors tend to be larger. I suspect this is because it’s using the 2-norm for convergence in the SNES, so, where the solution is already, the phase errors are seen as small too. Is there a way to use something more like an infinity norm with SNES, to get more point wise control?<br class=""><br class="">-gideon<br class=""><br class=""></blockquote><br class=""></div></div></blockquote></div><br class=""></div></div></div></body></html>