cvs: pear /Math_Matrix Matrix.php

jmcastagnetto Tue May 28 05:12:54 2002 EDT Modified files: /pear/Math_Matrix Matrix.php Log: Added recursive methods for calculation of determinant for N x N matrices Index: pear/Math_Matrix/Matrix.php diff -u pear/Math_Matrix/Matrix.php:1.2 pear/Math_Matrix/Matrix.php:1.3 --- pear/Math_Matrix/Matrix.php:1.2 Fri May 24 14:35:14 2002 +++ pear/Math_Matrix/Matrix.php Tue May 28 05:12:53 2002 @@ -18,7 +18,7 @@ // // Matrix definition and manipulation package // -// $Id: Matrix.php,v 1.2 2002/05/24 18:35:14 jmcastagnetto Exp $ +// $Id: Matrix.php,v 1.3 2002/05/28 09:12:53 jmcastagnetto Exp $ // require_once 'PEAR.php'; @@ -175,14 +175,14 @@ * @access public * @return mixed an array of integers on success, a PEAR_Error object otherwise */ - function getSize() { + function getSize() {/*{{{*/ if ($this->isEmpty()) return PEAR::raiseError('Matrix has not been populated'); else return array($this->_num_rows, $this->_num_cols); - } + }/*}}}*/ - function setElement($row, $col, $value) { + function setElement($row, $col, $value) {/*{{{*/ if ($this->isEmpty()) return PEAR::raiseError('Matrix has not been populated'); if ($row >= $this->_num_rows && $col >= $this->_num_cols) @@ -191,14 +191,49 @@ return PEAR::raiseError('Incorrect value, expecting a number'); $this->_data[$row][$col] = $value; return true; - } + }/*}}}*/ - function getElement($row, $col) { + function getElement($row, $col) {/*{{{*/ if ($this->isEmpty()) return PEAR::raiseError('Matrix has not been populated'); if ($row >= $this->_num_rows && $col >= $this->_num_cols) return PEAR::raiseError('Incorrect row and column values'); return $this->_data[$row][$col]; + }/*}}}*/ + + function determinant() { + if ($this->isEmpty()) + return PEAR::raiseError('Matrix has not been populated'); + if (!$this->isSquare()) + return PEAR::raiseError('Determinant undefined for non-square matrices'); + return _calcDet($arr); + } + + function _calcDet($arr) { + $n = count($arr); + $sum = 0; + $tarr = array(); + if ($n == 1) + return $arr[0][0]; + else if ($n == 2) + return ($arr[0][0] * $arr[1][1] - + $arr[1][0] * $arr[0][1]); + else + for ($i=0; $i < $n; $i++) { + if ($arr[0][$i] != 0) + for ($j=1; $j < $n; $j++) + for ($k=2; $k < $n; $k++) + if ($k > $i) + $tarr[$j - 1][$k - 1] = $arr[$j][$k]; + else if ($k < $i) + $tarr[$j - 1][$k] = $arr[$j][$k]; + $factor = $arr[1][$i] * $this->_calcDet($tarr); + if ($i % 2 == 0) + $sum -= $factor; + else + $sum += $factor; + } + return sum; } function getRow ($row) {/*{{{*/