How do you do sumproduct in PHP?

Question

	A	B
1	0.72	97.29
2	0.72	67.68
3	0.72	66.97
4	0.72	67.57
5	0.72	67.80
6	0.72	94.71
7	0.72	136.23
8	0.72	146.77
9	0.72	139.06
10	0.72	95.39
11	0.35	58.66
12	0.20	48.90
13	0.05	37.07
14	0.05	61.31
15	0.20	95.26
16	0.35	140.80
17	0.72	228.09
18	0.72	318.25
19	0.72	407.95
20	0.72	413.11
21	0.72	409.11
22	0.72	394.49
23	0.72	300.57
24	0.72	162.24

I need to work out this spreadsheet formula =SUMPRODUCT(A1:A24,B1:B24) in PHP.

This is what I tried (but I think my formula is incorrect)

$a = array( 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.35, 0.20, 0.05, 0.05, 0.20, 0.35, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72 );
$b = array( 97.29, 67.68, 66.97, 67.57, 67.80, 94.71, 136.23, 146.77, 139.06, 95.39, 58.66, 48.90, 37.07, 61.31, 95.26, 140.80, 228.09, 318.25, 407.95, 413.11, 409.11, 394.49, 300.57, 162.24 );

$a_total = 0;
$b_total = 0;

foreach( $a as $row ) {
    $a_total += $row;
}
foreach( $b as $row ) {
    $b_total += $row;
}

$sumproduct = $a_total * $b_total;

Answer 1

You're adding all the rows in each range and multiplying the result. That's not what SUMPRODUCT does.

You should be multiplying the corresponding elements from each array and totalling the results:

$a = array( 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.35, 0.20, 0.05, 0.05, 0.20, 0.35, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72, 0.72 );
$b = array( 97.29, 67.68, 66.97, 67.57, 67.80, 94.71, 136.23, 146.77, 139.06, 95.39, 58.66, 48.90, 37.07, 61.31, 95.26, 140.80, 228.09, 318.25, 407.95, 413.11, 409.11, 394.49, 300.57, 162.24 );

$sumProduct = 0;

for( $i = 0; $i<count($a); $i++ ) {
    $sumProduct += ($a[$i]*$b[$i]);
}

echo $sumProduct;

See https://3v4l.org/hkFhf

Of course, this is just one of the options for SUMPRODUCT. See the Microsoft docs for more options for SUMPRODUCT