假设我想在PHP中复制矩阵乘法的代码,我的矩阵看起来像:
$matrix_1 = array(array(1,2), array(3,4))
子阵列的数量( 2 )等于矩阵中的列数,而每个子阵列中的元素数量( 2 )表示的数量矩阵中的行。
代码需要:
我附加了幻灯片here,它解释了代码应该实现的目标(有两个例子)。
答案 0 :(得分:0)
这是我的(啰嗦)解决方案。我将试着看看我是否可以在某些地方简化这一点。请注意:
else
命令中只需包含一个count()
命令来识别一个(或多个)数组是否是标量并相应地应用乘法函数使用array_map
。代码:
<?php
// FUNCTIONS
function mul($x, $y){
return ($x * $y);
}
// Example Arrays
$array_1 = array(array(1,4,7), array(2,5,8), array(3,6,9));
$array_2 = array(array(7,6,4), array(5,8,1), array(4,3,2));
// Check for row/column equivalence
$array_1_cols = count($array_1);
$array_1_rows = count($array_1[0]);
$array_2_cols = count($array_2);
$array_2_rows = count($array_2[0]);
// Check to see if matrix multiplication is possible
if($array_1_cols == $array_2_rows) {
$m_cols = $array_2_cols;
$m_rows = $array_1_rows;
$array_3 = array();
$col_index = 1;
// Start loop for each column of the new matrix
while($col_index <= $m_cols) {
$m_col_index = $col_index - 1;
$sub_array[$col_index] = array();
// Start loop for each row of the new matrix
$row_index = 1;
while($row_index <= $m_rows) {
$m_row_index = $row_index - 1;
// Auxiliary array for each row of A
$a_row[$row_index] = array();
$a_index = 1;
while($a_index <= $array_1_cols) {
$start_p = $a_index - 1;
$el_part_[$a_index] = $array_1[$start_p];
$el_part_[$a_index] = $el_part_[$a_index][$m_row_index];
array_push($a_row[$row_index], $el_part_[$a_index]);
++$a_index;
}
// Array for columns of B
$b_col[$col_index] = $array_2[$m_col_index];
// Build matrix C - defined over the rows of A and the columns of B
$c_part[$row_index][$col_index] = array_map('mul', $a_row[$row_index], $b_col[$col_index]);
$c_el[$row_index][$col_index] = array_sum($c_part[$row_index][$col_index]);
array_push($sub_array[$col_index], $c_el[$row_index][$col_index]);
// End row loop
++$row_index;
}
array_push($array_3,$sub_array[$col_index]);
++$col_index;
}
print_r($array_3);
} else {
echo "This is not possible!";
}
?>