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<div id="version" align=right><b>slepc-3.22.2 2024-12-02</b></div>
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<H1>SVDComputeError</H1>
Computes the error (based on the residual norm) associated with the i-th singular triplet.
<H3><FONT COLOR="#883300">Synopsis</FONT></H3>
<PRE>
#include "slepcsvd.h"
<A HREF="https://petsc.org/release/manualpages/Sys/PetscErrorCode.html#PetscErrorCode">PetscErrorCode</A> <A HREF="../SVD/SVDComputeError.html#SVDComputeError">SVDComputeError</A>(<A HREF="../SVD/SVD.html#SVD">SVD</A> svd,<A HREF="https://petsc.org/release/manualpages/Sys/PetscInt.html#PetscInt">PetscInt</A> i,<A HREF="../SVD/SVDErrorType.html#SVDErrorType">SVDErrorType</A> type,<A HREF="https://petsc.org/release/manualpages/Sys/PetscReal.html#PetscReal">PetscReal</A> *error)
</PRE>
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>svd </B></TD><TD> - the singular value solver context
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>i </B></TD><TD> - the solution index
</TD></TR>
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>type </B></TD><TD> - the type of error to compute
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Output Parameter</FONT></H3>
<TABLE border="0" cellpadding="0" cellspacing="0">
<TR><TD WIDTH=40></TD><TD ALIGN=LEFT VALIGN=TOP><B>error </B></TD><TD> - the error
</TD></TR></TABLE>
<P>
<H3><FONT COLOR="#883300">Notes</FONT></H3>
The error can be computed in various ways, all of them based on the residual
norm obtained as sqrt(n1^2+n2^2) with n1 = ||A*v-sigma*u||_2 and
n2 = ||A^T*u-sigma*v||_2, where sigma is the singular value, u is the left
singular vector and v is the right singular vector.
<P>
In the case of the GSVD, the two components of the residual norm are
n1 = ||s^2*A'*u-c*B'*B*x||_2 and n2 = ||c^2*B'*v-s*A'*A*x||_2, where [u;v]
are the left singular vectors and x is the right singular vector, with
sigma=c/s.
<P>
<P>
<H3><FONT COLOR="#883300">See Also</FONT></H3>
<A HREF="../SVD/SVDErrorType.html#SVDErrorType">SVDErrorType</A>, <A HREF="../SVD/SVDSolve.html#SVDSolve">SVDSolve</A>()
<BR><P><B></B><H3><FONT COLOR="#883300">Level</FONT></H3>beginner<BR>
<H3><FONT COLOR="#883300">Location</FONT></H3>
</B><A HREF="../../../src/svd/interface/svdsolve.c.html#SVDComputeError">src/svd/interface/svdsolve.c</A>
<P><H3><FONT COLOR="#883300">Examples</FONT></H3>
<A HREF="../../../src/svd/tutorials/ex15.c.html">src/svd/tutorials/ex15.c</A><BR>
<A HREF="../../../src/svd/tutorials/ex15f.F90.html">src/svd/tutorials/ex15f.F90</A><BR>
<A HREF="../../../src/svd/tutorials/ex45.c.html">src/svd/tutorials/ex45.c</A><BR>
<BR><BR><A HREF="./index.html">Index of all SVD routines</A>
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