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<hr><h1>division_scs.c</h1><a href="division__scs_8c.html">Go to the documentation of this file.</a><div class="fragment"><pre>00001 <font class="comment">/** Functions for SCS inverse and division</font>
00002 <font class="comment"></font>
00003 <font class="comment">@file division_scs.c</font>
00004 <font class="comment"></font>
00005 <font class="comment">@author Defour David David.Defour@ens-lyon.fr</font>
00006 <font class="comment">@author Florent de Dinechin Florent.de.Dinechin@ens-lyon.fr </font>
00007 <font class="comment"> </font>
00008 <font class="comment">This file is part of the SCS library.</font>
00009 <font class="comment"></font>
00010 <font class="comment"></font>
00011 <font class="comment">*/</font>
00012
00013 <font class="comment">/*</font>
00014 <font class="comment">Copyright (C) 2002 David Defour and Florent de Dinechin</font>
00015 <font class="comment"></font>
00016 <font class="comment"> This library is free software; you can redistribute it and/or</font>
00017 <font class="comment"> modify it under the terms of the GNU Lesser General Public</font>
00018 <font class="comment"> License as published by the Free Software Foundation; either</font>
00019 <font class="comment"> version 2.1 of the License, or (at your option) any later version.</font>
00020 <font class="comment"></font>
00021 <font class="comment"> This library is distributed in the hope that it will be useful,</font>
00022 <font class="comment"> but WITHOUT ANY WARRANTY; without even the implied warranty of</font>
00023 <font class="comment"> MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU</font>
00024 <font class="comment"> Lesser General Public License for more details.</font>
00025 <font class="comment"></font>
00026 <font class="comment"> You should have received a copy of the GNU Lesser General Public</font>
00027 <font class="comment"> License along with this library; if not, write to the Free Software</font>
00028 <font class="comment"> Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA</font>
00029 <font class="comment"></font>
00030 <font class="comment"> */</font>
00031 <font class="preprocessor">#include "<a class="code" href="scs_8h.html">scs.h</a>"</font>
00032 <font class="preprocessor">#include "<a class="code" href="scs__private_8h.html">scs_private.h</a>"</font>
00033
00034
00035 <font class="comment">/*</font>
00036 <font class="comment"> * Compute 1/x with a Newton scheme</font>
00037 <font class="comment"> */</font>
<a name="l00038"></a><a class="code" href="division__scs_8c.html#a0">00038</a> <font class="keywordtype">void</font> <a class="code" href="division__scs_8c.html#a0">scs_inv</a>(<a class="code" href="structscs.html">scs_ptr</a> result, <a class="code" href="structscs.html">scs_ptr</a> x){
00039 <a class="code" href="scs_8h.html#a3">scs_t</a> tmp, res, res1, scstwo;
00040 <font class="keywordtype">double</font> app_x, inv;
00041
00042 <a class="code" href="addition__scs_8c.html#a0">scs_set</a>(tmp, x); tmp->index = 0; <a class="code" href="scs2double_8c.html#a0">scs_get_d</a>(&app_x, tmp);
00043
00044 <a class="code" href="double2scs_8c.html#a1">scs_set_si</a>(scstwo, 2);
00045 <font class="comment">/* inv is a 53-bit approximation of 1/x */</font>
00046 inv = 1/app_x;
00047
00048 <a class="code" href="double2scs_8c.html#a0">scs_set_d</a>(res, inv);
00049 res->index -= x-><a class="code" href="structscs.html#m2">index</a>;
00050
00051 <font class="comment">/* First Newton Iteration */</font>
00052 <a class="code" href="multiplication__scs_8c.html#a2">scs_mul</a>(res1, x, res);
00053 <a class="code" href="addition__scs_8c.html#a9">scs_sub</a>(res1, scstwo, res1);
00054 <a class="code" href="multiplication__scs_8c.html#a2">scs_mul</a>(res, res, res1);
00055
00056 <font class="comment">/* Second Newton Iteration */</font>
00057 <a class="code" href="multiplication__scs_8c.html#a2">scs_mul</a>(res1, x, res);
00058 <a class="code" href="addition__scs_8c.html#a9">scs_sub</a>(res1, scstwo, res1);
00059 <a class="code" href="multiplication__scs_8c.html#a2">scs_mul</a>(result, res, res1);
00060
00061 <font class="keywordflow">return</font>;
00062 }
00063
00064 <font class="comment">/*</font>
00065 <font class="comment"> * Compute result = x/y; </font>
00066 <font class="comment"> */</font>
<a name="l00067"></a><a class="code" href="division__scs_8c.html#a1">00067</a> <font class="keywordtype">void</font> <a class="code" href="division__scs_8c.html#a1">scs_div</a>(<a class="code" href="structscs.html">scs_ptr</a> result, <a class="code" href="structscs.html">scs_ptr</a> x, <a class="code" href="structscs.html">scs_ptr</a> y){
00068 <a class="code" href="scs_8h.html#a3">scs_t</a> res;
00069
00070 <font class="keywordflow">if</font> (X_EXP != 1){
00071 R_EXP = X_EXP / Y_EXP;
00072 <font class="keywordflow">return</font>;
00073 }
00074
00075 <a class="code" href="division__scs_8c.html#a0">scs_inv</a>(res, y);
00076 <a class="code" href="multiplication__scs_8c.html#a2">scs_mul</a>(result, res, x);
00077 <font class="keywordflow">return</font>;
00078 }
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