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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> |
| <table border="0" cellpadding="0" cellspacing="0"> |
| <tr><td></td></tr> |
| <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> |
| </table> |
| <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> |
| <div class="memitem"> |
| <div class="memproto"> |
| <table class="memname"> |
| <tr> |
| <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> |
| <tr> |
| <td class="paramkey"></td> |
| <td></td> |
| <td class="paramtype">double * </td> |
| <td class="paramname"> <em>r</em>, </td> |
| </tr> |
| <tr> |
| <td class="paramkey"></td> |
| <td></td> |
| <td class="paramtype">double * </td> |
| <td class="paramname"> <em>c</em>, </td> |
| </tr> |
| <tr> |
| <td class="paramkey"></td> |
| <td></td> |
| <td class="paramtype">double * </td> |
| <td class="paramname"> <em>rowcnd</em>, </td> |
| </tr> |
| <tr> |
| <td class="paramkey"></td> |
| <td></td> |
| <td class="paramtype">double * </td> |
| <td class="paramname"> <em>colcnd</em>, </td> |
| </tr> |
| <tr> |
| <td class="paramkey"></td> |
| <td></td> |
| <td class="paramtype">double * </td> |
| <td class="paramname"> <em>amax</em>, </td> |
| </tr> |
| <tr> |
| <td class="paramkey"></td> |
| <td></td> |
| <td class="paramtype">int * </td> |
| <td class="paramname"> <em>info</em></td><td> </td> |
| </tr> |
| <tr> |
| <td></td> |
| <td>)</td> |
| <td></td><td></td><td width="100%"></td> |
| </tr> |
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| <div class="memdoc"> |
| |
| <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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