java - Java - Double precision floating point

Question

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how to fix double precision issue in java

I have a small piece of code like this:

double number1 = 6;
double number2 = 5.99;
double result = number1 - number2;

However, the result == 0.009999999999999787 instead of 0.01

I know it is the issue of IEEE 754 standard, but I don't understand why. Could you please explain it for me?

Answer 1

This is because float point numbers cannot be exactly represented with in binary system with limited bits (not without precision loss)

See: http://en.wikipedia.org/wiki/Loss_of_significance

Answer 2

Because there is no .01 in floating point numbers. The fractional bits are expressed as 1/root 2 so you can get something like .0125 or what you have there but there is not .01 in floating point numbers. If you need exact precision use integers instead.