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<div id="version" align=right><b>slepc-3.23.1 2025-05-01</b></div>
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<H1>EPSEVSLSetDOSParameters</H1>
Defines the parameters used for computing the density of states (DOS) in the EVSL solver.
<H3><FONT COLOR="#883300">Synopsis</FONT></H3>
<PRE>
#include "slepceps.h"
<A HREF="https://petsc.org/release/manualpages/Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../EPS/EPSEVSLSetDOSParameters.html#EPSEVSLSetDOSParameters">EPSEVSLSetDOSParameters</A>(<A HREF="../EPS/EPS.html#EPS">EPS</A> eps,<A HREF="../EPS/EPSEVSLDOSMethod.html#EPSEVSLDOSMethod">EPSEVSLDOSMethod</A> dos,<A HREF="https://petsc.org/release/manualpages/Sys/PetscInt.html#PetscInt">PetscInt</A> nvec,<A HREF="https://petsc.org/release/manualpages/Sys/PetscInt.html#PetscInt">PetscInt</A> deg,<A HREF="https://petsc.org/release/manualpages/Sys/PetscInt.html#PetscInt">PetscInt</A> steps,<A HREF="https://petsc.org/release/manualpages/Sys/PetscInt.html#PetscInt">PetscInt</A> npoints)
</PRE>
Logically Collective
<P>
<H3><FONT COLOR="#883300">Input Parameters</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>eps </B></TD><TD> - the eigensolver context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>dos </B></TD><TD> - DOS method, either KPM or Lanczos
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>nvec </B></TD><TD> - number of sample vectors
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>deg </B></TD><TD> - polynomial degree (KPM only)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>steps </B></TD><TD> - number of Lanczos steps (Lanczos only)
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>npoints </B></TD><TD> - number of sample points (Lanczos only)
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Options Database Keys</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-eps_evsl_dos_method <dos> </B></TD><TD> - set the DOS method, either kpm or lanczos
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-eps_evsl_dos_nvec <n> </B></TD><TD> - set the number of sample vectors
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-eps_evsl_dos_degree <n> </B></TD><TD> - set the polynomial degree
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-eps_evsl_dos_steps <n> </B></TD><TD> - set the number of Lanczos steps
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>-eps_evsl_dos_npoints <n> </B></TD><TD> - set the number of sample points
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Notes</FONT></H3>
The density of states (or spectral density) can be approximated with two
methods, kernel polynomial method (KPM) or Lanczos. Some parameters for
these methods can be set by the user with this function, with some of
them being relevant for one of the methods only.
<P>
For the integer argumens, you can use <A HREF="https://petsc.org/release/manualpages/Sys/PETSC_CURRENT.html#PETSC_CURRENT">PETSC_CURRENT</A> to keep the current
value, and <A HREF="https://petsc.org/release/manualpages/Sys/PETSC_DETERMINE.html#PETSC_DETERMINE">PETSC_DETERMINE</A> to set them to a reasonable default.
<P>
<P>
<H3><FONT COLOR="#883300">See Also</FONT></H3>
<A HREF="../EPS/EPSEVSLGetDOSParameters.html#EPSEVSLGetDOSParameters">EPSEVSLGetDOSParameters</A>()
<BR><P><B></B><H3><FONT COLOR="#883300">Level</FONT></H3>intermediate<BR>
<H3><FONT COLOR="#883300">Location</FONT></H3>
</B><A HREF="../../../src/eps/impls/external/evsl/evsl.c.html#EPSEVSLSetDOSParameters">src/eps/impls/external/evsl/evsl.c</A>
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