参考链接

https://blog.csdn.net/weixin_42853272/article/details/84100505?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.nonecase&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.nonecase

代码

function decimalNotation($num)
{
$parts = explode('E', $num);
if(count($parts) != 2){
return $num;
}
$exp = abs(end($parts)) +3;
$decimal = number_format($num, $exp);
$decimal = rtrim($decimal, '0');
return rtrim($decimal, '.');
}