Question

I have this script…

//initial value

$fund = 10;
$rebate = 0.01; // constant 1 percent
$maturity = 30; //days

echo '<ul>';
echo '<li>Day1 fund: $' . $fund . '</li>';

//day1 value
$fund = incfund($fund); //should return $10.10
echo '<li>Day2 fund: $' . $fund . '</li>';

//day2 value
$fund = incfund($fund); //should return $10.20
echo '<li>Day3 fund: $' . $fund . '</li>';

//day3 value
$fund = incfund($fund); //should return $10.30
echo '<li>Day4 fund: $' . $fund . '</li>';

echo '</ul>';
//continue increasing the fund value daily until day 30...


//function to increase $fund

function incfund($x){
for($i = 0; $i<=$maturity; $i++){
$newfund = $x + $rebate;
$fund = $newfund;
return $fund;
}
}

currently if I run the script, it will output:

Day1 fund: $10
Day2 fund: $10
Day3 fund: $10
Day4 fund: $10

when I really want to output is:

Day1 fund: $10.10
Day2 fund: $10.20
Day3 fund: $10.30
Day4 fund: $10.40
...
...
Day30 fund: $13.00

basically, what I want to do is compute the 1% rebate and compound it to the original fund and then continue compounding until the maturity date.

what could be the problem why I cannot do what I want?

Answer 1

Look at your code

function incfund($x){
    for($i = 0; $i<=$maturity; $i++){
        $newfund = $x + $rebate;
        $fund = $newfund;
        return $fund;
    }
}

What it really do

function incfund($x){
    return $x+$rebate;
}

What you should change

function incfund($x){
    global $rebate;
    return $x+$rebate;
}

or

function incfund($x, $rebate){
    return $x+$rebate;
}

And change view layer for

for ($i = 1; $i <= $maturity; $i++, $fund = incfund($fund)) {
    echo '<li>Day'.$i.' fund: $' . $fund . '</li>';
}

But as you described your functionality all your code should look like

//initial value

$fund = 10;
$rebate_weekdays = 0.01; // constant 1 percent
$rebate_weekend = 0.02; // constant 1 percent
$maturity = 30; //days

echo '<ul>';

// show fund and continue increasing the fund value daily until day 30...
for ($i = 1; $i <= $maturity; $i++) {
    $rebate = (is_it_weekend($i)) ? $rebate_weekend: $rebate_weekdays;
    $curfund = incfund($fund, $i, $rebate);
    echo '<li>Day'.$i.' fund: $' . $curfund . '</li>';
}

echo '</ul>';

//function to calculate current $fund    
function incfund($fund, $x, $rebate){
    return $fund * (1 + $x * $rebate);
}

How to check that day you can find. It simply using http://php.net/mktime and http://php.net/date