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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML3.2 EN">
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<TITLE>SNESCubicLineSearch</TITLE>
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<A NAME="SNESCubicLineSearch"><H1>SNESCubicLineSearch</H1></A>
Performs a cubic line search (default line search method).
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
int SNESCubicLineSearch(SNES snes,void *lsctx,Vec x,Vec f,Vec g,Vec y,Vec w,PetscReal fnorm,PetscReal *ynorm,PetscReal *gnorm,int *flag)
</PRE>
Collective on <A HREF="../SNES/SNES.html#SNES">SNES</A>
<P>
<H3><FONT COLOR="#CC3333">Input Parameters</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>snes </B></TD><TD>- nonlinear context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>lsctx </B></TD><TD>- optional context for line search (not used here)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>x </B></TD><TD>- current iterate
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>f </B></TD><TD>- residual evaluated at x
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>y </B></TD><TD>- search direction (contains new iterate on output)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>w </B></TD><TD>- work vector
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>fnorm </B></TD><TD>- 2-norm of f
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Output Parameters</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>g </B></TD><TD>- residual evaluated at new iterate y
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>y </B></TD><TD>- new iterate (contains search direction on input)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>gnorm </B></TD><TD>- 2-norm of g
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>ynorm </B></TD><TD>- 2-norm of search length
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>flag </B></TD><TD>- 0 if line search succeeds; -1 on failure.
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Options Database Key</FONT></H3>
<pre>
-snes_ls cubic - Activates <A HREF="../SNES/SNESCubicLineSearch.html#SNESCubicLineSearch">SNESCubicLineSearch</A>()
</pre>
<P>
<H3><FONT COLOR="#CC3333">Notes</FONT></H3>
This line search is taken from "Numerical Methods for Unconstrained
Optimization and Nonlinear Equations" by Dennis and Schnabel, page 325.
<P>
<P>
<H3><FONT COLOR="#CC3333">Keywords</FONT></H3>
<A HREF="../SNES/SNES.html#SNES">SNES</A>, nonlinear, line search, cubic
<BR>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../SNES/SNESQuadraticLineSearch.html#SNESQuadraticLineSearch">SNESQuadraticLineSearch</A>(), <A HREF="../SNES/SNESNoLineSearch.html#SNESNoLineSearch">SNESNoLineSearch</A>(), <A HREF="../SNES/SNESSetLineSearch.html#SNESSetLineSearch">SNESSetLineSearch</A>(), <A HREF="../SNES/SNESNoLineSearchNoNorms.html#SNESNoLineSearchNoNorms">SNESNoLineSearchNoNorms</A>()
<BR><P><B><P><B><FONT COLOR="#CC3333">Level:</FONT></B>advanced
<BR><FONT COLOR="#CC3333">Location:</FONT></B><A HREF="../../../src/snes/impls/ls/ls.c.html#SNESCubicLineSearch">src/snes/impls/ls/ls.c</A>
<BR><A HREF="./index.html">Index of all SNES routines</A>
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