How random order some numbers by seed?The order not change if I not change the seed

$arr = [1，2，3，4，5];

$seed=100;
myRand($arr,$seed);//45123
myRand($arr,$seed);//45123
......             45123

$seed=10;
myRand($arr,$seed);//25431
myRand($arr,$seed);//25431
.......            25431

The order not change in the next invoke until I change The $seed.