perl -MData::IEEE754::Tools=ulp -le "printf qq{ULP(%s = %22.13a) = %.17e = %22.13a\n}, $_, $_, ulp($_), ulp($_) for 0.5,0.3,0.1"
ULP(0.5 =   0x1.0000000000000p-1) = 1.11022302462515654e-16 =  0x1.0000000000000p-53
ULP(0.3 =   0x1.3333333333333p-2) = 5.55111512312578270e-17 =  0x1.0000000000000p-54
ULP(0.1 =   0x1.999999999999ap-4) = 1.38777878078144568e-17 =  0x1.0000000000000p-56