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<h1>SRC/dlacon.c File Reference</h1>Estimates the 1-norm. <a href="#_details">More...</a>
<p>
<code>#include <math.h></code><br>
<code>#include "<a class="el" href="slu__Cnames_8h-source.html">slu_Cnames.h</a>"</code><br>
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<tr><td colspan="2"><br><h2>Defines</h2></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">#define </td><td class="memItemRight" valign="bottom"><a class="el" href="dlacon_8c.html#51b3babab7bbf03500dbc5ede2a682b3">d_sign</a>(a, b) (b >= 0 ? fabs(a) : -fabs(a))</td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">#define </td><td class="memItemRight" valign="bottom"><a class="el" href="dlacon_8c.html#dccc1e5692ca1dd160d0ca2a17e1b12c">i_dnnt</a>(a) ( a>=0 ? floor(a+.5) : -floor(.5-a) )</td></tr>
<tr><td colspan="2"><br><h2>Functions</h2></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">int </td><td class="memItemRight" valign="bottom"><a class="el" href="dlacon_8c.html#4187621e84a9554552e3fa8098542801">dlacon_</a> (int *n, double *v, double *x, int *isgn, double *est, int *kase)</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> <hr><h2>Define Documentation</h2>
<a class="anchor" name="51b3babab7bbf03500dbc5ede2a682b3"></a><!-- doxytag: member="dlacon.c::d_sign" ref="51b3babab7bbf03500dbc5ede2a682b3" args="(a, b)" -->
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<td class="memname">#define d_sign </td>
<td>(</td>
<td class="paramtype">a, <tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">b </td>
<td class="paramname"> </td>
<td> ) </td>
<td width="100%"> (b >= 0 ? fabs(a) : -fabs(a))</td>
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<a class="anchor" name="dccc1e5692ca1dd160d0ca2a17e1b12c"></a><!-- doxytag: member="dlacon.c::i_dnnt" ref="dccc1e5692ca1dd160d0ca2a17e1b12c" args="(a)" -->
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<td class="memname">#define i_dnnt </td>
<td>(</td>
<td class="paramtype">a </td>
<td class="paramname"> </td>
<td> ) </td>
<td width="100%"> ( a>=0 ? floor(a+.5) : -floor(.5-a) )</td>
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<hr><h2>Function Documentation</h2>
<a class="anchor" name="4187621e84a9554552e3fa8098542801"></a><!-- doxytag: member="dlacon.c::dlacon_" ref="4187621e84a9554552e3fa8098542801" args="(int *n, double *v, double *x, int *isgn, double *est, int *kase)" -->
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<td class="memname">int dlacon_ </td>
<td>(</td>
<td class="paramtype">int * </td>
<td class="paramname"> <em>n</em>, </td>
</tr>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">double * </td>
<td class="paramname"> <em>v</em>, </td>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">double * </td>
<td class="paramname"> <em>x</em>, </td>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">int * </td>
<td class="paramname"> <em>isgn</em>, </td>
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<td class="paramkey"></td>
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<td class="paramtype">double * </td>
<td class="paramname"> <em>est</em>, </td>
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<td class="paramkey"></td>
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<td class="paramtype">int * </td>
<td class="paramname"> <em>kase</em></td><td> </td>
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<pre>
Purpose
=======</pre><p>
<pre> DLACON estimates the 1-norm of a square matrix A.
Reverse communication is used for evaluating matrix-vector products.</pre><p>
<pre> Arguments
=========</pre><p>
<pre> N (input) INT
The order of the matrix. N >= 1.</pre><p>
<pre> V (workspace) DOUBLE PRECISION array, dimension (N)
On the final return, V = A*W, where EST = norm(V)/norm(W)
(W is not returned).</pre><p>
<pre> X (input/output) DOUBLE PRECISION array, dimension (N)
On an intermediate return, X should be overwritten by
A * X, if KASE=1,
A' * X, if KASE=2,
and DLACON must be re-called with all the other parameters
unchanged.</pre><p>
<pre> ISGN (workspace) INT array, dimension (N)</pre><p>
<pre> EST (output) DOUBLE PRECISION
An estimate (a lower bound) for norm(A).</pre><p>
<pre> KASE (input/output) INT
On the initial call to DLACON, KASE should be 0.
On an intermediate return, KASE will be 1 or 2, indicating
whether X should be overwritten by A * X or A' * X.
On the final return from DLACON, KASE will again be 0.</pre><p>
<pre> Further Details
======= =======</pre><p>
<pre> Contributed by Nick Higham, University of Manchester.
Originally named CONEST, dated March 16, 1988.</pre><p>
<pre> Reference: N.J. Higham, "FORTRAN codes for estimating the one-norm of
a real or <a class="el" href="structcomplex.html">complex</a> matrix, with applications to condition estimation",
ACM Trans. Math. Soft., vol. 14, no. 4, pp. 381-396, December 1988.
=====================================================================
</pre>
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