get__perm__c_8c.html

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          <td class="md" nowrap valign="top">void get_colamd           </td>
          <td class="md" valign="top">(&nbsp;</td>
          <td class="md" nowrap valign="top">const int&nbsp;</td>
          <td class="mdname" nowrap> <em>m</em>, </td>
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          <td class="md" nowrap>int *&nbsp;</td>
          <td class="mdname" nowrap> <em>rowind</em>, </td>
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          <td class="md" nowrap>int *&nbsp;</td>
          <td class="mdname" nowrap> <em>perm_c</em></td>
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<a class="anchor" name="aecb6e6e7a3e97356050bcfdf2573796"></a><!-- doxytag: member="get_perm_c.c::get_perm_c" ref="aecb6e6e7a3e97356050bcfdf2573796" args="(int ispec, SuperMatrix *A, int *perm_c)" --><p>
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          <td class="md" nowrap valign="top">void get_perm_c           </td>
          <td class="md" valign="top">(&nbsp;</td>
          <td class="md" nowrap valign="top">int&nbsp;</td>
          <td class="mdname" nowrap> <em>ispec</em>, </td>
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          <td class="md" nowrap align="right"></td>
          <td class="md"></td>
          <td class="md" nowrap><a class="el" href="structSuperMatrix.html">SuperMatrix</a> *&nbsp;</td>
          <td class="mdname" nowrap> <em>A</em>, </td>
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          <td class="md"></td>
          <td class="md" nowrap>int *&nbsp;</td>
          <td class="mdname" nowrap> <em>perm_c</em></td>
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          <td class="md">)&nbsp;</td>
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<p>
<pre>
 Purpose
 =======</pre><p>
<pre> GET_PERM_C obtains a permutation matrix Pc, by applying the multiple
 minimum degree ordering code by Joseph Liu to matrix A'*A or A+A'.
 or using approximate minimum degree column ordering by Davis et. al.
 The LU factorization of A*Pc tends to have less fill than the LU 
 factorization of A.</pre><p>
<pre> Arguments
 =========</pre><p>
<pre> ispec   (input) int
         Specifies the type of column ordering to reduce fill:
         = 1: minimum degree on the structure of A^T * A
         = 2: minimum degree on the structure of A^T + A
         = 3: approximate minimum degree for unsymmetric matrices
         If ispec == 0, the natural ordering (i.e., Pc = I) is returned.</pre><p>
<pre> A       (input) SuperMatrix*
         Matrix A in A*X=B, of dimension (A-&gt;nrow, A-&gt;ncol). The number
         of the linear equations is A-&gt;nrow. Currently, the type of A 
         can be: Stype = NC; Dtype = _D; Mtype = GE. In the future,
         more general A can be handled.</pre><p>
<pre> perm_c  (output) int*
	   Column permutation vector of size A-&gt;ncol, which defines the 
         permutation matrix Pc; perm_c[i] = j means column i of A is 
         in position j in A*Pc.
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<a class="anchor" name="90f30e2b284864f6a800a98ceaff8fbc"></a><!-- doxytag: member="get_perm_c.c::getata" ref="90f30e2b284864f6a800a98ceaff8fbc" args="(const int m, const int n, const int nz, int *colptr, int *rowind, int *atanz, int **ata_colptr, int **ata_rowind)" --><p>
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          <td class="md" nowrap valign="top">void getata           </td>
          <td class="md" valign="top">(&nbsp;</td>
          <td class="md" nowrap valign="top">const int&nbsp;</td>
          <td class="mdname" nowrap> <em>m</em>, </td>
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          <td class="md"></td>
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          <td class="mdname" nowrap> <em>n</em>, </td>
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          <td class="md" nowrap align="right"></td>
          <td class="md"></td>
          <td class="md" nowrap>const int&nbsp;</td>
          <td class="mdname" nowrap> <em>nz</em>, </td>
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          <td class="md" nowrap align="right"></td>
          <td class="md"></td>
          <td class="md" nowrap>int *&nbsp;</td>
          <td class="mdname" nowrap> <em>colptr</em>, </td>
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          <td class="md" nowrap align="right"></td>
          <td class="md"></td>
          <td class="md" nowrap>int *&nbsp;</td>
          <td class="mdname" nowrap> <em>rowind</em>, </td>
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          <td class="md" nowrap align="right"></td>
          <td class="md"></td>
          <td class="md" nowrap>int *&nbsp;</td>
          <td class="mdname" nowrap> <em>atanz</em>, </td>
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          <td class="md" nowrap align="right"></td>
          <td class="md"></td>
          <td class="md" nowrap>int **&nbsp;</td>
          <td class="mdname" nowrap> <em>ata_colptr</em>, </td>
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          <td class="md" nowrap align="right"></td>
          <td class="md"></td>
          <td class="md" nowrap>int **&nbsp;</td>
          <td class="mdname" nowrap> <em>ata_rowind</em></td>
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          <td class="md"></td>
          <td class="md">)&nbsp;</td>
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<p>
<pre>
 Purpose
 =======</pre><p>
<pre> Form the structure of A'*A. A is an m-by-n matrix in column oriented
 format represented by (colptr, rowind). The output A'*A is in column
 oriented format (symmetrically, also row oriented), represented by
 (ata_colptr, ata_rowind).</pre><p>
<pre> This routine is modified from GETATA routine by Tim Davis.
 The complexity of this algorithm is: SUM_{i=1,m} r(i)^2,
 i.e., the sum of the square of the row counts.</pre><p>
<pre> Questions
 =========
     o  Do I need to withhold the *dense* rows?
     o  How do I know the number of nonzeros in A'*A?
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