1){ $dServer[]=$data[1]; $labels[]=""; //$row-1; } $row++; } fclose($handle); } $st=mt_rand(0,$row-3-99); //-4 can provide length enough for 5 $output1 = array_slice($dServer, $st, 100); $labels = array_slice($labels, 1, 100); foreach($output1 as $key => $num) { if ($key>0) $devs[] = abs($num - $output1[$key-1]); } $mean = array_sum($devs) / count($devs); $sd=standard_deviation($devs); //$sd=standard_innovation($output1); $mx=max($devs); //$mn=0; //$output2[]=mt_rand($mn,$mx); $output2[]=$output1[0]; for ($i = 1; $i <= 99; $i++) { //$trans=normalrand()*$sd+$mean; $trans=purebell(-$mx, $mx,$sd,0.01); $output2[$i]=$output2[$i-1]+$trans;//$output2[$i-1]+$trans; } $answer=mt_rand(0,1); if ($answer==0){ $output0=$output2; $output2=$output1; $output1=$output0; } $serial1=serialize($output1); $serial2=serialize($output2); $hash=sha1(microtime(true).mt_rand(10000,90000)); //$client_ip=ipstuff(); $client_ip=$_SERVER['REMOTE_ADDR']; if ($client_ip=="::1") $client_ip="127.0.0.1"; $client_ip = ip2long($client_ip); $result = mysqli_query($con,"INSERT INTO randomwalks (walk1, walk2, random,useranswer,uhash,startindex,filen,ip) VALUES ('$serial1','$serial2',$answer+1,0,'$hash',$st,$filen,$client_ip)"); function standard_deviation($sample){ if(is_array($sample)){ $mean = array_sum($sample) / count($sample); foreach($sample as $key => $num) $devs[$key] = pow($num - $mean, 2); return sqrt(array_sum($devs) / (count($devs) - 1)); } } function standard_innovation($sample){ if(is_array($sample)){ foreach($sample as $key => $num) { if ($key>0) $devs[$key] = abs($num - $sample[$key-1]); } return array_sum($devs) / (count($devs) - 2); } } function purebell($min,$max,$std_deviation,$step=1) { $rand1 = (float)mt_rand()/(float)mt_getrandmax(); $rand2 = (float)mt_rand()/(float)mt_getrandmax(); $gaussian_number = sqrt(-2 * log($rand1)) * cos(2 * M_PI * $rand2); $mean = ($max + $min) / 2; $random_number = ($gaussian_number * $std_deviation) + $mean; $random_number = round($random_number / $step) * $step; if($random_number < $min || $random_number > $max) { $random_number = purebell($min, $max,$std_deviation); } return $random_number; } function normalrand(){ $randmax = 9999; $v = 2; while ($v > 1) { $u1 = rand(0, $randmax) / $randmax; $u2 = rand(0, $randmax) / $randmax; $v = (2 * $u1 - 1) * (2 * $u1 - 1) + (2 * $u2 - 1) * (2 * $u2 - 1); } return (2* $u1 - 1) * (( -2 * log($v) / $v) ^ 0.5); } ?> Line Chart
Can you spot a random walk?*





* One of the lines is a random sample of 100 consecutive days for the price of a specific stock.
The other one is a random walk. Which one's which?
Guess, read more on random walks and the set up here or go back to my page.