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Micro optimization for matrix multiplication (#255)

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* Micro optimization for matrix multiplication

* code cs fix

* added a comment block for the change
This commit is contained in:
Mustafa Karabulut 2018-03-08 20:19:09 +02:00 committed by Arkadiusz Kondas
parent e156076539
commit 0d80c78c57
1 changed files with 16 additions and 7 deletions
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23
src/Math/Matrix.php
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@ -142,15 +142,24 @@ class Matrix
throw new InvalidArgumentException('Inconsistent matrix supplied'); throw new InvalidArgumentException('Inconsistent matrix supplied');
} }
$array1 = $this->toArray();
$array2 = $matrix->toArray();
$colCount = $matrix->columns;
/*
- To speed-up multiplication, we need to avoid use of array index operator [ ] as much as possible( See #255 for details)
- A combination of "foreach" and "array_column" works much faster then accessing the array via index operator
*/
$product = []; $product = [];
$multiplier = $matrix->toArray(); foreach ($array1 as $row => $rowData) {
for ($i = 0; $i < $this->rows; ++$i) { for ($col = 0; $col < $colCount; ++$col) {
$columns = $matrix->getColumns(); $columnData = array_column($array2, $col);
for ($j = 0; $j < $columns; ++$j) { $sum = 0;
$product[$i][$j] = 0; foreach ($rowData as $key => $valueData) {
for ($k = 0; $k < $this->columns; ++$k) { $sum += $valueData * $columnData[$key];
$product[$i][$j] += $this->matrix[$i][$k] * $multiplier[$k][$j];
} }
$product[$row][$col] = $sum;
} }
} }