PHP How To Calculate Yearly Increase by Given Start and End Year - php

Question

By given 2 range of year, current population and target population, how to get total population every year by using PHP?
Example:
Year | Population
2014 | 100000
2018 | 132000
On paper calculation like this:
132000 / 100000 = 1.0718
so we will get result every year (On paper):
2014 = 100000
2015 = 107187 (100000 * 1.0718)
2016 = 114890 (107187 * 1.0718)
2017 = 123147 (114890 * 1.0718)
2018 = 132000
How to hold previous year variable to get result as above?
This is my PHP code:
for($i > $start; $i < $end; $i++) {
$this->ProjectPopulation->create();
$increase = array(
'project_id' => $project_id,
'year' => $i,
'percent_increase' => $this->percentage_increase($current_population, $target_population, $year),
'population' => ??? // Problem here
);
$this->ProjectPopulation->save($increase);
}
Thanks

Answer 1

There are two resources I'd recommend you taking a look at:
http://php.net/manual/en/ref.math.php
and
http://www.w3schools.com/php/php_ref_math.asp
You can solve this by doing the calculation each time, but it would be faster to use a loop in order to iterate through them all.
So something like this:
$population = 100000;
$year = 2014;
//I'd print the first one out prior to the loop, or you could put an if($year == 2014) in the loop, your choice really.
for(i= 0; i < 4; i++)
{
//do calculation in here.
echo "The current years is" . $year;
$yearsCalculation = $population * 1.0718;
//then save that value for the next time around the loop.
$population = $yearsCalculation ;
echo $yearsCalculation ;
//increase years each time round loop
$year++;
}
If you then want to store it in a MySQL database you might want to have a look at this tutorial:
http://www.w3schools.com/php/php_mysql_insert.asp
Hope that helped!

Answer 2

Solve
private function power($current_population, $target_population, $year) {
$devide = $target_population / $current_population;
$pwrdevider = 1 / $year;
$power = pow($devide, $pwrdevider);
return $power;
}
private function percentage_increase($current_population, $target_population, $year) {
$devide = $target_population / $current_population;
$power = pow($devide, 1 / $year);
$increase = ($power - 1) * 100;
return $increase;
}
$start = 2014;
$end = 2018;
$diff = $end - $start;
for($i = 1, $data = 100000; $i <= $diff; $i++) {
$data *= $this->power(100000, 132000, $diff);
$increase = array(
'project_id' => 1,
'year' => $start += 1,
'percent_increase' => $this->percentage_increase(100000, 132000, $diff),
'population' => $data
);
print_r($increase);
}
This is my result
Array
(
[project_id] => 1
[year] => 2015
[percent_increase] => 7.1873373728262
[population] => 107187.33737283
)
Array
(
[project_id] => 1
[year] => 2016
[percent_increase] => 7.1873373728262
[population] => 114891.25293076
)
Array
(
[project_id] => 1
[year] => 2017
[percent_increase] => 7.1873373728262
[population] => 123148.87489076
)
Array
(
[project_id] => 1
[year] => 2018
[percent_increase] => 7.1873373728262
[population] => 132000
)
Thanks all