How to print power series in php

Question

A function with the following signature: function exponentArr($num) { }

Such that when $num = 10, the function returns an array of

[1,2,4,8,16,32,64,128,256,512,1024]

Whats your question? Edit: Are you just copy/pasting your homework or something? Show some effort, you have 1.3k karma, you should know better. — Dan Smith, Jan 28 '15 at 11:34
possible duplicate of [Raising to power in PHP](http://stackoverflow.com/questions/1211514/raising-to-power-in-php) — Asik, Jan 28 '15 at 12:16

Moid · Accepted Answer · 2015-01-28T11:47:30.940

5

You can do this:

function exponentArr($num){
    $arr = array();
    for($i=0;$i <= $num;$i++){
        $arr[$i] = pow(2, $i);
    }
    return $arr;
}

This will give you an array $arr with the required output.

edited Jan 28 '15 at 11:47

answered Jan 28 '15 at 11:38

Moid

it is simply raising 2's power...from 0 to upto `$num` – Moid Jan 28 '15 at 11:39
`$i < $num` Should be `$i <= $num` – Bart Haalstra Jan 28 '15 at 11:46

score -2 · Answer 2 · answered Jan 28 '15 at 11:48

-2

Try this, Working as you mentioned.

function powArr($number){
    for($i=0;$i < $number;$i++){
        $array[$i] = pow(2, $i);
    }
    return $array;
}

answered Jan 28 '15 at 11:48

Vivek Sharma

This is (almost) the same as Moid's answer, except his is correct, more complete and has an explanation. -1. – Styphon Jan 28 '15 at 11:50

score -3 · Answer 3 · answered Jan 28 '15 at 11:38

-3

This is Fibonacci sequence

Try this:

$fib = [1,0];
for($i=0; $i<$num; $i++) {
    $next = array_sum($fib);
    array_shift($fib);
    array_push($fib,$next);
    echo $next.", ";
}

answered Jan 28 '15 at 11:38

Ruben Lech

No, it's not the Fibonacci sequence. The Fibonacci sequence is 1,1,2,3,5,8,13,21,34... – Styphon Jan 28 '15 at 11:47
He is not asking for fibonicci – Gaurav Dave Jan 28 '15 at 12:52

3 Answers3