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<h1>SRC/dgsequ.c File Reference</h1>Computes row and column scalings. <a href="#_details">More...</a>
<p>
<code>#include <math.h></code><br>
<code>#include "<a class="el" href="slu__ddefs_8h-source.html">slu_ddefs.h</a>"</code><br>
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<tr><td colspan="2"><br><h2>Functions</h2></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="dgsequ_8c.html#af22b247cc134fb0ba90285e84ccebb4">dgsequ</a> (<a class="el" href="structSuperMatrix.html">SuperMatrix</a> *<a class="el" href="ilu__zdrop__row_8c.html#c900805a486cbb8489e3c176ed6e0d8e">A</a>, double *r, double *c, double *rowcnd, double *colcnd, double *amax, int *info)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Driver related. <a href="#af22b247cc134fb0ba90285e84ccebb4"></a><br></td></tr>
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<hr><a name="_details"></a><h2>Detailed Description</h2>
<pre>
-- SuperLU routine (version 2.0) --
Univ. of California Berkeley, Xerox Palo Alto Research Center,
and Lawrence Berkeley National Lab.
November 15, 1997</pre><p>
<pre> Modified from LAPACK routine DGEEQU
</pre> <hr><h2>Function Documentation</h2>
<a class="anchor" name="af22b247cc134fb0ba90285e84ccebb4"></a><!-- doxytag: member="dgsequ.c::dgsequ" ref="af22b247cc134fb0ba90285e84ccebb4" args="(SuperMatrix *A, double *r, double *c, double *rowcnd, double *colcnd, double *amax, int *info)" -->
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<td class="memname">void dgsequ </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structSuperMatrix.html">SuperMatrix</a> * </td>
<td class="paramname"> <em>A</em>, </td>
</tr>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">double * </td>
<td class="paramname"> <em>r</em>, </td>
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<td class="paramkey"></td>
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<td class="paramtype">double * </td>
<td class="paramname"> <em>c</em>, </td>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">double * </td>
<td class="paramname"> <em>rowcnd</em>, </td>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">double * </td>
<td class="paramname"> <em>colcnd</em>, </td>
</tr>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">double * </td>
<td class="paramname"> <em>amax</em>, </td>
</tr>
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<td class="paramkey"></td>
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<td class="paramtype">int * </td>
<td class="paramname"> <em>info</em></td><td> </td>
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<td>)</td>
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<p>
<pre>
Purpose
=======</pre><p>
<pre> DGSEQU computes row and column scalings intended to equilibrate an
M-by-N sparse matrix A and reduce its condition number. R returns the row
scale factors and C the column scale factors, chosen to try to make
the largest element in each row and column of the matrix B with
elements B(i,j)=R(i)*A(i,j)*C(j) have absolute value 1.</pre><p>
<pre> R(i) and C(j) are restricted to be between SMLNUM = smallest safe
number and BIGNUM = largest safe number. Use of these scaling
factors is not guaranteed to reduce the condition number of A but
works well in practice.</pre><p>
<pre> See <a class="el" href="supermatrix_8h.html" title="Defines matrix types.">supermatrix.h</a> for the definition of 'SuperMatrix' structure.</pre><p>
<pre> Arguments
=========</pre><p>
<pre> A (input) SuperMatrix*
The matrix of dimension (A->nrow, A->ncol) whose equilibration
factors are to be computed. The type of A can be:
Stype = SLU_NC; Dtype = SLU_D; Mtype = SLU_GE.</pre><p>
<pre> R (output) double*, size A->nrow
If INFO = 0 or INFO > M, R contains the row scale factors
for A.</pre><p>
<pre> C (output) double*, size A->ncol
If INFO = 0, C contains the column scale factors for A.</pre><p>
<pre> ROWCND (output) double*
If INFO = 0 or INFO > M, ROWCND contains the ratio of the
smallest R(i) to the largest R(i). If ROWCND >= 0.1 and
AMAX is neither too large nor too small, it is not worth
scaling by R.</pre><p>
<pre> COLCND (output) double*
If INFO = 0, COLCND contains the ratio of the smallest
C(i) to the largest C(i). If COLCND >= 0.1, it is not
worth scaling by C.</pre><p>
<pre> AMAX (output) double*
Absolute value of largest matrix element. If AMAX is very
close to overflow or very close to underflow, the matrix
should be scaled.</pre><p>
<pre> INFO (output) int*
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, and i is
<= A->nrow: the i-th row of A is exactly zero
> A->ncol: the (i-M)-th column of A is exactly zero</pre><p>
<pre> =====================================================================
</pre>
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