sizeof(double) is 8
y is 1.000000
y is 1.666667
y is 2.333333
y is 3.000000
y is 3.666667
y is 4.333333
y is 5.000000
y is 5.666667
y is 6.333333
y is 7.000000
y is 7.666667
y is 8.333333
y is 9.000000
y is 9.666667