php wrong equation infinity result

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mohamed86medo

the equation is

@N means N^N + N^(N+1) + N^(N+2) + ... + N^(N+9)

Find the sum of digits in @321

so i made a little program that first calculate @N

$n = 321;
$res = 0;

for($i=0;$i<10;$i++){

$res = $res + bcpow($n,$n+$i);

}

echo $res;

i get INF !!!
so why the result is infinity ?

OctoberWind

Your results are overflowing.

321¹⁰⁰ = 4.472015e+250

that's 250 zeros, and im only raising it to the 100th power. You want to raise it to the 321st power?

9³²¹ = 2.050433e+306

That's as big as Google's calculator will go...

NogDog

My guess is you're simply generating numbers too large for PHP to handle? 321³²¹ = 321 321 321 * 321...[317 more times!], and just 321⁴ = 10,617,447,681.

mohamed86medo

at first i thought there is something with memory exhausted !

and when i trying to just add two parts like [ N^N + N^(N+1) ] it also give INF !!!

but this equation has a solution and now how to solve this equation ??

this equation is here

http://tournament.arabnet.me/challenge/

in web developer challenge

NogDog

It might simply be that you need to use bc*() functions for all arithmetic operations, not just the bcpow(). Otherwise you'll be exceeding the max PHP integer size (32 or 64 bit unsigned integer).

$n = 321;
$res = 0;
for($i=0;$i<10;$i++){
  $res = bcadd($res, bcpow($n, bcadd($n, $i)));
}
echo $res;

mohamed86medo

Thank you very much

it's working fine and i got a result