normal: x_1= 999.99900000, x_2= 0.00100708
x_2 -> -0.00707901
cared : x_1= 999.99900000, x_2= 0.00100000
x_2 -> 0.00000006

f(x) = x^2 - 1000x + c = 0
normal: x_1= 999.99900000, x_2= 0.00100708
f(x_2) -> -0.00707901
cared : x_1= 999.99900000, x_2= 0.00100000
f(x_2) -> 0.00000006

Update "cancellation of significant digits" example
Update "cancellation of significant digits" example
