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<?php |
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/** |
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* @package JAMA |
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* |
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* For an m-by-n matrix A with m >= n, the singular value decomposition is |
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* an m-by-n orthogonal matrix U, an n-by-n diagonal matrix S, and |
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* an n-by-n orthogonal matrix V so that A = U*S*V'. |
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* |
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* The singular values, sigma[$k] = S[$k][$k], are ordered so that |
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* sigma[0] >= sigma[1] >= ... >= sigma[n-1]. |
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* |
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* The singular value decompostion always exists, so the constructor will |
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* never fail. The matrix condition number and the effective numerical |
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* rank can be computed from this decomposition. |
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* |
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* @author Paul Meagher |
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* @license PHP v3.0 |
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* @version 1.1 |
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*/ |
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class SingularValueDecomposition { |
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/** |
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* Internal storage of U. |
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* @var array |
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*/ |
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private $U = array(); |
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/** |
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* Internal storage of V. |
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* @var array |
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*/ |
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private $V = array(); |
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/** |
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* Internal storage of singular values. |
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* @var array |
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*/ |
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private $s = array(); |
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/** |
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* Row dimension. |
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* @var int |
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*/ |
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private $m; |
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/** |
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* Column dimension. |
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* @var int |
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*/ |
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private $n; |
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/** |
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* Construct the singular value decomposition |
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* |
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* Derived from LINPACK code. |
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* |
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* @param $A Rectangular matrix |
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* @return Structure to access U, S and V. |
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*/ |
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public function __construct($Arg) { |
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// Initialize. |
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$A = $Arg->getArrayCopy(); |
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$this->m = $Arg->getRowDimension(); |
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$this->n = $Arg->getColumnDimension(); |
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$nu = min($this->m, $this->n); |
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$e = array(); |
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$work = array(); |
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$wantu = true; |
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$wantv = true; |
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$nct = min($this->m - 1, $this->n); |
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$nrt = max(0, min($this->n - 2, $this->m)); |
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// Reduce A to bidiagonal form, storing the diagonal elements |
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// in s and the super-diagonal elements in e. |
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for ($k = 0; $k < max($nct,$nrt); ++$k) { |
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if ($k < $nct) { |
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// Compute the transformation for the k-th column and |
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// place the k-th diagonal in s[$k]. |
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// Compute 2-norm of k-th column without under/overflow. |
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$this->s[$k] = 0; |
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for ($i = $k; $i < $this->m; ++$i) { |
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$this->s[$k] = hypo($this->s[$k], $A[$i][$k]); |
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} |
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if ($this->s[$k] != 0.0) { |
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if ($A[$k][$k] < 0.0) { |
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$this->s[$k] = -$this->s[$k]; |
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} |
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for ($i = $k; $i < $this->m; ++$i) { |
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$A[$i][$k] /= $this->s[$k]; |
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} |
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$A[$k][$k] += 1.0; |
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} |
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$this->s[$k] = -$this->s[$k]; |
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} |
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for ($j = $k + 1; $j < $this->n; ++$j) { |
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if (($k < $nct) & ($this->s[$k] != 0.0)) { |
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// Apply the transformation. |
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$t = 0; |
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for ($i = $k; $i < $this->m; ++$i) { |
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$t += $A[$i][$k] * $A[$i][$j]; |
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} |
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$t = -$t / $A[$k][$k]; |
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for ($i = $k; $i < $this->m; ++$i) { |
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$A[$i][$j] += $t * $A[$i][$k]; |
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} |
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// Place the k-th row of A into e for the |
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// subsequent calculation of the row transformation. |
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$e[$j] = $A[$k][$j]; |
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} |
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} |
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if ($wantu AND ($k < $nct)) { |
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// Place the transformation in U for subsequent back |
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// multiplication. |
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for ($i = $k; $i < $this->m; ++$i) { |
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$this->U[$i][$k] = $A[$i][$k]; |
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} |
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} |
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if ($k < $nrt) { |
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// Compute the k-th row transformation and place the |
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// k-th super-diagonal in e[$k]. |
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// Compute 2-norm without under/overflow. |
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$e[$k] = 0; |
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for ($i = $k + 1; $i < $this->n; ++$i) { |
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$e[$k] = hypo($e[$k], $e[$i]); |
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} |
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if ($e[$k] != 0.0) { |
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if ($e[$k+1] < 0.0) { |
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$e[$k] = -$e[$k]; |
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} |
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for ($i = $k + 1; $i < $this->n; ++$i) { |
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$e[$i] /= $e[$k]; |
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} |
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$e[$k+1] += 1.0; |
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} |
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$e[$k] = -$e[$k]; |
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if (($k+1 < $this->m) AND ($e[$k] != 0.0)) { |
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// Apply the transformation. |
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View Code Duplication |
for ($i = $k+1; $i < $this->m; ++$i) { |
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$work[$i] = 0.0; |
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} |
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for ($j = $k+1; $j < $this->n; ++$j) { |
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for ($i = $k+1; $i < $this->m; ++$i) { |
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$work[$i] += $e[$j] * $A[$i][$j]; |
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} |
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} |
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for ($j = $k + 1; $j < $this->n; ++$j) { |
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$t = -$e[$j] / $e[$k+1]; |
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for ($i = $k + 1; $i < $this->m; ++$i) { |
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$A[$i][$j] += $t * $work[$i]; |
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} |
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} |
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} |
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View Code Duplication |
if ($wantv) { |
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// Place the transformation in V for subsequent |
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// back multiplication. |
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for ($i = $k + 1; $i < $this->n; ++$i) { |
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$this->V[$i][$k] = $e[$i]; |
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} |
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} |
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} |
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} |
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// Set up the final bidiagonal matrix or order p. |
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$p = min($this->n, $this->m + 1); |
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if ($nct < $this->n) { |
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$this->s[$nct] = $A[$nct][$nct]; |
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} |
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if ($this->m < $p) { |
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$this->s[$p-1] = 0.0; |
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} |
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if ($nrt + 1 < $p) { |
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$e[$nrt] = $A[$nrt][$p-1]; |
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} |
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$e[$p-1] = 0.0; |
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// If required, generate U. |
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if ($wantu) { |
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for ($j = $nct; $j < $nu; ++$j) { |
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for ($i = 0; $i < $this->m; ++$i) { |
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$this->U[$i][$j] = 0.0; |
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} |
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$this->U[$j][$j] = 1.0; |
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} |
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for ($k = $nct - 1; $k >= 0; --$k) { |
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if ($this->s[$k] != 0.0) { |
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View Code Duplication |
for ($j = $k + 1; $j < $nu; ++$j) { |
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$t = 0; |
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for ($i = $k; $i < $this->m; ++$i) { |
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$t += $this->U[$i][$k] * $this->U[$i][$j]; |
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} |
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$t = -$t / $this->U[$k][$k]; |
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for ($i = $k; $i < $this->m; ++$i) { |
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$this->U[$i][$j] += $t * $this->U[$i][$k]; |
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} |
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} |
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for ($i = $k; $i < $this->m; ++$i ) { |
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$this->U[$i][$k] = -$this->U[$i][$k]; |
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} |
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$this->U[$k][$k] = 1.0 + $this->U[$k][$k]; |
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View Code Duplication |
for ($i = 0; $i < $k - 1; ++$i) { |
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$this->U[$i][$k] = 0.0; |
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} |
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} else { |
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View Code Duplication |
for ($i = 0; $i < $this->m; ++$i) { |
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$this->U[$i][$k] = 0.0; |
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} |
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$this->U[$k][$k] = 1.0; |
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} |
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} |
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} |
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// If required, generate V. |
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if ($wantv) { |
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for ($k = $this->n - 1; $k >= 0; --$k) { |
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if (($k < $nrt) AND ($e[$k] != 0.0)) { |
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for ($j = $k + 1; $j < $nu; ++$j) { |
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$t = 0; |
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for ($i = $k + 1; $i < $this->n; ++$i) { |
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$t += $this->V[$i][$k]* $this->V[$i][$j]; |
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} |
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$t = -$t / $this->V[$k+1][$k]; |
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for ($i = $k + 1; $i < $this->n; ++$i) { |
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$this->V[$i][$j] += $t * $this->V[$i][$k]; |
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} |
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} |
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} |
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View Code Duplication |
for ($i = 0; $i < $this->n; ++$i) { |
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$this->V[$i][$k] = 0.0; |
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} |
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$this->V[$k][$k] = 1.0; |
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} |
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} |
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// Main iteration loop for the singular values. |
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$pp = $p - 1; |
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$iter = 0; |
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$eps = pow(2.0, -52.0); |
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244
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while ($p > 0) { |
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// Here is where a test for too many iterations would go. |
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// This section of the program inspects for negligible |
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// elements in the s and e arrays. On completion the |
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// variables kase and k are set as follows: |
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// kase = 1 if s(p) and e[k-1] are negligible and k<p |
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// kase = 2 if s(k) is negligible and k<p |
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// kase = 3 if e[k-1] is negligible, k<p, and |
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// s(k), ..., s(p) are not negligible (qr step). |
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// kase = 4 if e(p-1) is negligible (convergence). |
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for ($k = $p - 2; $k >= -1; --$k) { |
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if ($k == -1) { |
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256
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break; |
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257
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} |
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258
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if (abs($e[$k]) <= $eps * (abs($this->s[$k]) + abs($this->s[$k+1]))) { |
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$e[$k] = 0.0; |
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break; |
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261
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} |
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262
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} |
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263
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if ($k == $p - 2) { |
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264
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$kase = 4; |
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265
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} else { |
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266
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for ($ks = $p - 1; $ks >= $k; --$ks) { |
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267
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if ($ks == $k) { |
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268
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break; |
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} |
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270
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$t = ($ks != $p ? abs($e[$ks]) : 0.) + ($ks != $k + 1 ? abs($e[$ks-1]) : 0.); |
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271
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if (abs($this->s[$ks]) <= $eps * $t) { |
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$this->s[$ks] = 0.0; |
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273
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break; |
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274
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} |
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275
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} |
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276
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if ($ks == $k) { |
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277
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$kase = 3; |
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278
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} else if ($ks == $p-1) { |
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279
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$kase = 1; |
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280
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} else { |
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281
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$kase = 2; |
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282
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$k = $ks; |
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} |
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284
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} |
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285
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++$k; |
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286
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287
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// Perform the task indicated by kase. |
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288
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switch ($kase) { |
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289
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// Deflate negligible s(p). |
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290
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case 1: |
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291
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$f = $e[$p-2]; |
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292
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$e[$p-2] = 0.0; |
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293
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for ($j = $p - 2; $j >= $k; --$j) { |
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294
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$t = hypo($this->s[$j],$f); |
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295
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$cs = $this->s[$j] / $t; |
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296
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$sn = $f / $t; |
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297
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$this->s[$j] = $t; |
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298
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|
|
if ($j != $k) { |
|
299
|
|
|
$f = -$sn * $e[$j-1]; |
|
300
|
|
|
$e[$j-1] = $cs * $e[$j-1]; |
|
301
|
|
|
} |
|
302
|
|
View Code Duplication |
if ($wantv) { |
|
303
|
|
|
for ($i = 0; $i < $this->n; ++$i) { |
|
304
|
|
|
$t = $cs * $this->V[$i][$j] + $sn * $this->V[$i][$p-1]; |
|
305
|
|
|
$this->V[$i][$p-1] = -$sn * $this->V[$i][$j] + $cs * $this->V[$i][$p-1]; |
|
306
|
|
|
$this->V[$i][$j] = $t; |
|
307
|
|
|
} |
|
308
|
|
|
} |
|
309
|
|
|
} |
|
310
|
|
|
break; |
|
311
|
|
|
// Split at negligible s(k). |
|
312
|
|
|
case 2: |
|
313
|
|
|
$f = $e[$k-1]; |
|
314
|
|
|
$e[$k-1] = 0.0; |
|
315
|
|
|
for ($j = $k; $j < $p; ++$j) { |
|
316
|
|
|
$t = hypo($this->s[$j], $f); |
|
317
|
|
|
$cs = $this->s[$j] / $t; |
|
318
|
|
|
$sn = $f / $t; |
|
319
|
|
|
$this->s[$j] = $t; |
|
320
|
|
|
$f = -$sn * $e[$j]; |
|
321
|
|
|
$e[$j] = $cs * $e[$j]; |
|
322
|
|
View Code Duplication |
if ($wantu) { |
|
323
|
|
|
for ($i = 0; $i < $this->m; ++$i) { |
|
324
|
|
|
$t = $cs * $this->U[$i][$j] + $sn * $this->U[$i][$k-1]; |
|
325
|
|
|
$this->U[$i][$k-1] = -$sn * $this->U[$i][$j] + $cs * $this->U[$i][$k-1]; |
|
326
|
|
|
$this->U[$i][$j] = $t; |
|
327
|
|
|
} |
|
328
|
|
|
} |
|
329
|
|
|
} |
|
330
|
|
|
break; |
|
331
|
|
|
// Perform one qr step. |
|
332
|
|
|
case 3: |
|
333
|
|
|
// Calculate the shift. |
|
334
|
|
|
$scale = max(max(max(max( |
|
335
|
|
|
abs($this->s[$p-1]),abs($this->s[$p-2])),abs($e[$p-2])), |
|
336
|
|
|
abs($this->s[$k])), abs($e[$k])); |
|
337
|
|
|
$sp = $this->s[$p-1] / $scale; |
|
338
|
|
|
$spm1 = $this->s[$p-2] / $scale; |
|
339
|
|
|
$epm1 = $e[$p-2] / $scale; |
|
340
|
|
|
$sk = $this->s[$k] / $scale; |
|
341
|
|
|
$ek = $e[$k] / $scale; |
|
342
|
|
|
$b = (($spm1 + $sp) * ($spm1 - $sp) + $epm1 * $epm1) / 2.0; |
|
343
|
|
|
$c = ($sp * $epm1) * ($sp * $epm1); |
|
344
|
|
|
$shift = 0.0; |
|
345
|
|
|
if (($b != 0.0) || ($c != 0.0)) { |
|
346
|
|
|
$shift = sqrt($b * $b + $c); |
|
347
|
|
|
if ($b < 0.0) { |
|
348
|
|
|
$shift = -$shift; |
|
349
|
|
|
} |
|
350
|
|
|
$shift = $c / ($b + $shift); |
|
351
|
|
|
} |
|
352
|
|
|
$f = ($sk + $sp) * ($sk - $sp) + $shift; |
|
353
|
|
|
$g = $sk * $ek; |
|
354
|
|
|
// Chase zeros. |
|
355
|
|
|
for ($j = $k; $j < $p-1; ++$j) { |
|
356
|
|
|
$t = hypo($f,$g); |
|
357
|
|
|
$cs = $f/$t; |
|
358
|
|
|
$sn = $g/$t; |
|
359
|
|
|
if ($j != $k) { |
|
360
|
|
|
$e[$j-1] = $t; |
|
361
|
|
|
} |
|
362
|
|
|
$f = $cs * $this->s[$j] + $sn * $e[$j]; |
|
363
|
|
|
$e[$j] = $cs * $e[$j] - $sn * $this->s[$j]; |
|
364
|
|
|
$g = $sn * $this->s[$j+1]; |
|
365
|
|
|
$this->s[$j+1] = $cs * $this->s[$j+1]; |
|
366
|
|
View Code Duplication |
if ($wantv) { |
|
367
|
|
|
for ($i = 0; $i < $this->n; ++$i) { |
|
368
|
|
|
$t = $cs * $this->V[$i][$j] + $sn * $this->V[$i][$j+1]; |
|
369
|
|
|
$this->V[$i][$j+1] = -$sn * $this->V[$i][$j] + $cs * $this->V[$i][$j+1]; |
|
370
|
|
|
$this->V[$i][$j] = $t; |
|
371
|
|
|
} |
|
372
|
|
|
} |
|
373
|
|
|
$t = hypo($f,$g); |
|
374
|
|
|
$cs = $f/$t; |
|
375
|
|
|
$sn = $g/$t; |
|
376
|
|
|
$this->s[$j] = $t; |
|
377
|
|
|
$f = $cs * $e[$j] + $sn * $this->s[$j+1]; |
|
378
|
|
|
$this->s[$j+1] = -$sn * $e[$j] + $cs * $this->s[$j+1]; |
|
379
|
|
|
$g = $sn * $e[$j+1]; |
|
380
|
|
|
$e[$j+1] = $cs * $e[$j+1]; |
|
381
|
|
View Code Duplication |
if ($wantu && ($j < $this->m - 1)) { |
|
382
|
|
|
for ($i = 0; $i < $this->m; ++$i) { |
|
383
|
|
|
$t = $cs * $this->U[$i][$j] + $sn * $this->U[$i][$j+1]; |
|
384
|
|
|
$this->U[$i][$j+1] = -$sn * $this->U[$i][$j] + $cs * $this->U[$i][$j+1]; |
|
385
|
|
|
$this->U[$i][$j] = $t; |
|
386
|
|
|
} |
|
387
|
|
|
} |
|
388
|
|
|
} |
|
389
|
|
|
$e[$p-2] = $f; |
|
390
|
|
|
$iter = $iter + 1; |
|
391
|
|
|
break; |
|
392
|
|
|
// Convergence. |
|
393
|
|
|
case 4: |
|
394
|
|
|
// Make the singular values positive. |
|
395
|
|
|
if ($this->s[$k] <= 0.0) { |
|
396
|
|
|
$this->s[$k] = ($this->s[$k] < 0.0 ? -$this->s[$k] : 0.0); |
|
397
|
|
View Code Duplication |
if ($wantv) { |
|
398
|
|
|
for ($i = 0; $i <= $pp; ++$i) { |
|
399
|
|
|
$this->V[$i][$k] = -$this->V[$i][$k]; |
|
400
|
|
|
} |
|
401
|
|
|
} |
|
402
|
|
|
} |
|
403
|
|
|
// Order the singular values. |
|
404
|
|
|
while ($k < $pp) { |
|
405
|
|
|
if ($this->s[$k] >= $this->s[$k+1]) { |
|
406
|
|
|
break; |
|
407
|
|
|
} |
|
408
|
|
|
$t = $this->s[$k]; |
|
409
|
|
|
$this->s[$k] = $this->s[$k+1]; |
|
410
|
|
|
$this->s[$k+1] = $t; |
|
411
|
|
View Code Duplication |
if ($wantv AND ($k < $this->n - 1)) { |
|
|
|
|
|
|
412
|
|
|
for ($i = 0; $i < $this->n; ++$i) { |
|
413
|
|
|
$t = $this->V[$i][$k+1]; |
|
414
|
|
|
$this->V[$i][$k+1] = $this->V[$i][$k]; |
|
415
|
|
|
$this->V[$i][$k] = $t; |
|
416
|
|
|
} |
|
417
|
|
|
} |
|
418
|
|
View Code Duplication |
if ($wantu AND ($k < $this->m-1)) { |
|
|
|
|
|
|
419
|
|
|
for ($i = 0; $i < $this->m; ++$i) { |
|
420
|
|
|
$t = $this->U[$i][$k+1]; |
|
421
|
|
|
$this->U[$i][$k+1] = $this->U[$i][$k]; |
|
422
|
|
|
$this->U[$i][$k] = $t; |
|
423
|
|
|
} |
|
424
|
|
|
} |
|
425
|
|
|
++$k; |
|
426
|
|
|
} |
|
427
|
|
|
$iter = 0; |
|
428
|
|
|
--$p; |
|
429
|
|
|
break; |
|
430
|
|
|
} // end switch |
|
431
|
|
|
} // end while |
|
432
|
|
|
|
|
433
|
|
|
} // end constructor |
|
434
|
|
|
|
|
435
|
|
|
|
|
436
|
|
|
/** |
|
437
|
|
|
* Return the left singular vectors |
|
438
|
|
|
* |
|
439
|
|
|
* @access public |
|
440
|
|
|
* @return U |
|
441
|
|
|
*/ |
|
442
|
|
|
public function getU() { |
|
443
|
|
|
return new Matrix($this->U, $this->m, min($this->m + 1, $this->n)); |
|
444
|
|
|
} |
|
445
|
|
|
|
|
446
|
|
|
|
|
447
|
|
|
/** |
|
448
|
|
|
* Return the right singular vectors |
|
449
|
|
|
* |
|
450
|
|
|
* @access public |
|
451
|
|
|
* @return V |
|
452
|
|
|
*/ |
|
453
|
|
|
public function getV() { |
|
454
|
|
|
return new Matrix($this->V); |
|
455
|
|
|
} |
|
456
|
|
|
|
|
457
|
|
|
|
|
458
|
|
|
/** |
|
459
|
|
|
* Return the one-dimensional array of singular values |
|
460
|
|
|
* |
|
461
|
|
|
* @access public |
|
462
|
|
|
* @return diagonal of S. |
|
463
|
|
|
*/ |
|
464
|
|
|
public function getSingularValues() { |
|
465
|
|
|
return $this->s; |
|
466
|
|
|
} |
|
467
|
|
|
|
|
468
|
|
|
|
|
469
|
|
|
/** |
|
470
|
|
|
* Return the diagonal matrix of singular values |
|
471
|
|
|
* |
|
472
|
|
|
* @access public |
|
473
|
|
|
* @return S |
|
474
|
|
|
*/ |
|
475
|
|
|
public function getS() { |
|
476
|
|
|
for ($i = 0; $i < $this->n; ++$i) { |
|
477
|
|
|
for ($j = 0; $j < $this->n; ++$j) { |
|
478
|
|
|
$S[$i][$j] = 0.0; |
|
|
|
|
|
|
479
|
|
|
} |
|
480
|
|
|
$S[$i][$i] = $this->s[$i]; |
|
|
|
|
|
|
481
|
|
|
} |
|
482
|
|
|
return new Matrix($S); |
|
483
|
|
|
} |
|
484
|
|
|
|
|
485
|
|
|
|
|
486
|
|
|
/** |
|
487
|
|
|
* Two norm |
|
488
|
|
|
* |
|
489
|
|
|
* @access public |
|
490
|
|
|
* @return max(S) |
|
|
|
|
|
|
491
|
|
|
*/ |
|
492
|
|
|
public function norm2() { |
|
493
|
|
|
return $this->s[0]; |
|
494
|
|
|
} |
|
495
|
|
|
|
|
496
|
|
|
|
|
497
|
|
|
/** |
|
498
|
|
|
* Two norm condition number |
|
499
|
|
|
* |
|
500
|
|
|
* @access public |
|
501
|
|
|
* @return max(S)/min(S) |
|
|
|
|
|
|
502
|
|
|
*/ |
|
503
|
|
|
public function cond() { |
|
504
|
|
|
return $this->s[0] / $this->s[min($this->m, $this->n) - 1]; |
|
505
|
|
|
} |
|
506
|
|
|
|
|
507
|
|
|
|
|
508
|
|
|
/** |
|
509
|
|
|
* Effective numerical matrix rank |
|
510
|
|
|
* |
|
511
|
|
|
* @access public |
|
512
|
|
|
* @return Number of nonnegligible singular values. |
|
513
|
|
|
*/ |
|
514
|
|
|
public function rank() { |
|
515
|
|
|
$eps = pow(2.0, -52.0); |
|
516
|
|
|
$tol = max($this->m, $this->n) * $this->s[0] * $eps; |
|
517
|
|
|
$r = 0; |
|
518
|
|
|
for ($i = 0; $i < count($this->s); ++$i) { |
|
|
|
|
|
|
519
|
|
|
if ($this->s[$i] > $tol) { |
|
520
|
|
|
++$r; |
|
521
|
|
|
} |
|
522
|
|
|
} |
|
523
|
|
|
return $r; |
|
524
|
|
|
} |
|
525
|
|
|
|
|
526
|
|
|
} // class SingularValueDecomposition |
|
527
|
|
|
|