public function PHPExcel_Shared_JAMA_LUDecomposition::__construct in Loft Data Grids 6.2
Same name and namespace in other branches
- 7.2 vendor/phpoffice/phpexcel/Classes/PHPExcel/Shared/JAMA/LUDecomposition.php \PHPExcel_Shared_JAMA_LUDecomposition::__construct()
* LU Decomposition constructor. * *
Parameters
$A Rectangular matrix: * @return Structure to access L, U and piv.
File
- vendor/
phpoffice/ phpexcel/ Classes/ PHPExcel/ Shared/ JAMA/ LUDecomposition.php, line 63
Class
- PHPExcel_Shared_JAMA_LUDecomposition
- @package JAMA
Code
public function __construct($A) {
if ($A instanceof PHPExcel_Shared_JAMA_Matrix) {
// Use a "left-looking", dot-product, Crout/Doolittle algorithm.
$this->LU = $A
->getArray();
$this->m = $A
->getRowDimension();
$this->n = $A
->getColumnDimension();
for ($i = 0; $i < $this->m; ++$i) {
$this->piv[$i] = $i;
}
$this->pivsign = 1;
$LUrowi = $LUcolj = array();
// Outer loop.
for ($j = 0; $j < $this->n; ++$j) {
// Make a copy of the j-th column to localize references.
for ($i = 0; $i < $this->m; ++$i) {
$LUcolj[$i] =& $this->LU[$i][$j];
}
// Apply previous transformations.
for ($i = 0; $i < $this->m; ++$i) {
$LUrowi = $this->LU[$i];
// Most of the time is spent in the following dot product.
$kmax = min($i, $j);
$s = 0.0;
for ($k = 0; $k < $kmax; ++$k) {
$s += $LUrowi[$k] * $LUcolj[$k];
}
$LUrowi[$j] = $LUcolj[$i] -= $s;
}
// Find pivot and exchange if necessary.
$p = $j;
for ($i = $j + 1; $i < $this->m; ++$i) {
if (abs($LUcolj[$i]) > abs($LUcolj[$p])) {
$p = $i;
}
}
if ($p != $j) {
for ($k = 0; $k < $this->n; ++$k) {
$t = $this->LU[$p][$k];
$this->LU[$p][$k] = $this->LU[$j][$k];
$this->LU[$j][$k] = $t;
}
$k = $this->piv[$p];
$this->piv[$p] = $this->piv[$j];
$this->piv[$j] = $k;
$this->pivsign = $this->pivsign * -1;
}
// Compute multipliers.
if ($j < $this->m && $this->LU[$j][$j] != 0.0) {
for ($i = $j + 1; $i < $this->m; ++$i) {
$this->LU[$i][$j] /= $this->LU[$j][$j];
}
}
}
}
else {
throw new PHPExcel_Calculation_Exception(PHPExcel_Shared_JAMA_Matrix::ArgumentTypeException);
}
}