public function testMultiply()
{
$identity = $this->getIdentityMatrix($this->size);
$array = array();
for ($i = 0; $i < $this->size; $i++) {
for ($j = 0; $j < $this->size; $j++) {
$array[$i][$j] = rand();
}
}
$matrix = new LL_Matrix($array);
if ($this->strassen) {
$result = $matrix->strassenMultiply($identity);
} else {
$result = $matrix->naiveMultiply($identity);
}
}
public function testMultiply()
{
$identity3 = $this->getIdentityMatrix();
$input = array(array(1, 2, 3), array(3, 2, 1), array(1, 2, 1));
$matrix = new LL_Matrix($input);
$result = $matrix->multiply($identity3);
for ($i = 0; $i < count($input); $i++) {
for ($j = 0; $j < count($input[0]); $j++) {
$this->assertEquals($result->get($i, $j), $input[$i][$j]);
// identity multiplication should have no effect
}
}
$result = $matrix->multiply(new LL_Matrix($input));
// test multiplying by itself.
$this->assertNotEquals($result, false);
$this->assertEquals($result->get(0, 0), 10);
$this->assertEquals($result->get(0, 1), 12);
$this->assertEquals($result->get(0, 2), 8);
$this->assertEquals($result->get(1, 0), 10);
$this->assertEquals($result->get(1, 1), 12);
$this->assertEquals($result->get(1, 2), 12);
$this->assertEquals($result->get(2, 0), 8);
$this->assertEquals($result->get(2, 1), 8);
$this->assertEquals($result->get(2, 2), 6);
// test uneven shapes
$input = array(array(1, 2, 3), array(0, 2, 0));
$input2 = array(array(1, 2), array(2, 2), array(1, 1));
$matrix = new LL_Matrix($input);
$matrix2 = new LL_Matrix($input2);
$this->assertEquals($matrix->multiply($matrix), false);
$this->assertEquals($matrix2->multiply($matrix2), false);
$result = $matrix->multiply($matrix2);
$correct = array(array(8, 9), array(4, 4));
for ($i = 0; $i < count($correct); $i++) {
for ($j = 0; $j < count($correct[0]); $j++) {
$this->assertEquals($result->get($i, $j), $correct[$i][$j]);
}
}
$result = $matrix2->multiply($matrix);
$this->assertEquals($result->rows(), 3);
$this->assertEquals($result->columns(), 3);
}
public function naiveMultiply(LL_Matrix $matrix)
{
if (is_array($matrix)) {
$matrix = new LL_Matrix($matrix);
}
if ($this->columns() != $matrix->rows()) {
// impossible operation.
return false;
}
$result = array();
for ($a = 0; $a < $this->rows(); $a++) {
for ($b = 0; $b < $matrix->columns(); $b++) {
$result[$a][$b] = 0;
for ($i = 0; $i < $this->columns(); $i++) {
$result[$a][$b] += $this->get($a, $i) * $matrix->get($i, $b);
}
}
}
return new LL_Matrix($result);
}
