get() public method

Returns a sliced part the NumArray
Since: 1.0.0
public get ( ) : NumArray
return NumArray
 /**
  * @param NumArray $matrix
  * @param NumArray $vector
  * @return NumArray
  */
 protected static function backSubstitution(NumArray $matrix, NumArray $vector)
 {
     $shape = $matrix->getShape();
     $xVector = \NumPHP\Core\NumPHP::zeros($shape[0]);
     for ($i = $shape[0] - 1; $i >= 0; $i--) {
         $sum = 0;
         for ($j = $i + 1; $j < $shape[0]; $j++) {
             $sum += $matrix->get($i, $j)->dot($xVector->get($j))->getData();
         }
         $xVector->set($i, ($vector->get($i)->getData() - $sum) / $matrix->get($i, $i)->getData());
     }
     return $xVector;
 }
Example #2
0
 /**
  * Tests NumArray::get with argument 0 on vector with size 1
  */
 public function testGet1Args0()
 {
     $numArray = new NumArray([1]);
     $expectedNumArray = new NumArray(1);
     $this->assertNumArrayEquals($expectedNumArray, $numArray->get(0));
 }
Example #3
0
 /**
  * Searches the pivot index in an array
  *
  * @param NumArray $numArray given array
  * @param int      $iIndex   index
  *
  * @return int
  *
  * @since 1.0.0
  */
 protected static function getPivotIndex(NumArray $numArray, $iIndex)
 {
     $shape = $numArray->getShape();
     $mAxis = $shape[0];
     $max = abs($numArray->get($iIndex, $iIndex)->getData());
     $maxIndex = $iIndex;
     for ($j = $iIndex + 1; $j < $mAxis; $j++) {
         $abs = abs($numArray->get($j, $iIndex)->getData());
         if ($abs > $max) {
             $max = $abs;
             $maxIndex = $j;
         }
     }
     return $maxIndex;
 }
Example #4
0
 /**
  * Back Substitution solves a linear system with a upper triangular matrix of
  * size n*n and a vector of size n or a matrix of size n*m
  *
  * @param NumArray $uMatrix   upper triangular matrix of size n*n
  * @param NumArray $numArray  vector of size n or matrix of size n*m
  *
  * @return NumArray
  *
  * @since 1.0.0
  */
 protected static function backSubstitution(NumArray $uMatrix, NumArray $numArray)
 {
     $shape = $numArray->getShape();
     if (Helper::isVector($numArray)) {
         $xVector = NumPHP::zerosLike($numArray);
         for ($i = $shape[0] - 1; $i >= 0; $i--) {
             $slice = sprintf("%d:%d", $i + 1, $shape[0]);
             $sum = $uMatrix->get($i, $slice)->dot($xVector->get($slice));
             $xVector->set($i, $numArray->get($i)->sub($sum)->div($uMatrix->get($i, $i)));
         }
         return $xVector;
     }
     // $numArray is a matrix
     $copy = clone $numArray;
     for ($i = 0; $i < $shape[1]; $i++) {
         $copy->set(':', $i, self::backSubstitution($uMatrix, $copy->get(':', $i)));
     }
     return $copy;
 }