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<TITLE>TSAlpha2SetParams</TITLE>
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<div id="version" align=right><b>petsc-3.10.3 2018-12-18</b></div>
<div id="bugreport" align=right><a href="mailto:petsc-maint@mcs.anl.gov?subject=Typo or Error in Documentation &body=Please describe the typo or error in the documentation: petsc-3.10.3 v3.10.3 docs/manualpages/TS/TSAlpha2SetParams.html "><small>Report Typos and Errors</small></a></div>
<A NAME="TSAlpha2SetParams"><H1>TSAlpha2SetParams</H1></A>
sets the algorithmic parameters for <A HREF="../TS/TSALPHA2.html#TSALPHA2">TSALPHA2</A>
<H3><FONT COLOR="#CC3333">Synopsis</FONT></H3>
<PRE>
#include "petscts.h"
<A HREF="../Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../TS/TSAlpha2SetParams.html#TSAlpha2SetParams">TSAlpha2SetParams</A>(<A HREF="../TS/TS.html#TS">TS</A> ts,<A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> alpha_m,<A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> alpha_f,<A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> gamma,<A HREF="../Sys/PetscReal.html#PetscReal">PetscReal</A> beta)
</PRE>
Logically Collective on <A HREF="../TS/TS.html#TS">TS</A>
<P>
<H3><FONT COLOR="#CC3333">Second-order accuracy can be obtained so long as</FONT></H3>
\gamma = 1/2 + alpha_m - alpha_f
\beta = 1/4 (1 + alpha_m - alpha_f)^2
<P>
<H3><FONT COLOR="#CC3333">Unconditional stability requires</FONT></H3>
\alpha_m >= \alpha_f >= 1/2
<P>
<P>
<H3><FONT COLOR="#CC3333">Input Parameter</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>ts </B></TD><TD>- timestepping context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>\alpha_m </B></TD><TD>- algorithmic paramenter
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>\alpha_f </B></TD><TD>- algorithmic paramenter
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>\gamma </B></TD><TD>- algorithmic paramenter
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>\beta </B></TD><TD>- algorithmic paramenter
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#CC3333">Options Database</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-ts_alpha_alpha_m <alpha_m></B></TD><TD>- . -ts_alpha_alpha_f <alpha_f>
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-ts_alpha_gamma <gamma></B></TD><TD>- - -ts_alpha_beta <beta>
</TD></TR>
<P>
<H3><FONT COLOR="#CC3333">Note</FONT></H3>
Use of this function is normally only required to hack <A HREF="../TS/TSALPHA2.html#TSALPHA2">TSALPHA2</A> to
use a modified integration scheme. Users should call
<A HREF="../TS/TSAlpha2SetRadius.html#TSAlpha2SetRadius">TSAlpha2SetRadius</A>() to set the desired spectral radius of the methods
(i.e. high-frequency damping) in order so select optimal values for
these parameters.
<P>
<P>
<H3><FONT COLOR="#CC3333">See Also</FONT></H3>
<A HREF="../TS/TSAlpha2SetRadius.html#TSAlpha2SetRadius">TSAlpha2SetRadius</A>(), <A HREF="../TS/TSAlpha2GetParams.html#TSAlpha2GetParams">TSAlpha2GetParams</A>()
<BR><P><B></B><H3><FONT COLOR="#CC3333">Level</FONT></H3>advanced<BR>
<H3><FONT COLOR="#CC3333">Location</FONT></H3>
</B><A HREF="../../../src/ts/impls/implicit/alpha/alpha2.c.html#TSAlpha2SetParams">src/ts/impls/implicit/alpha/alpha2.c</A>
<P><H3><FONT COLOR="CC3333">Implementations</FONT></H3><A HREF="../../../src/ts/impls/implicit/alpha/alpha2.c.html#TSAlpha2SetParams_Alpha">TSAlpha2SetParams_Alpha in src/ts/impls/implicit/alpha/alpha2.c</A><BR>
<BR><A HREF="./index.html">Index of all TS routines</A>
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