public static double abs (double a)

Returns the absolute value of a ` double`

value.
If the argument is not negative, the argument is returned.
If the argument is negative, the negation of the argument is returned.
Special cases:

- If the argument is positive zero or negative zero, the result is positive zero.
- If the argument is infinite, the result is positive infinity.
- If the argument is NaN, the result is NaN.

`a` | the argument whose absolute value is to be determined |

@apiNote As implied by the above, one valid implementation of
this method is given by the expression below which computes a
` double`

with the same exponent and significand as the
argument but with a guaranteed zero sign bit indicating a
positive value:

` Double.longBitsToDouble((Double.doubleToRawLongBits(a)<<1)>>>1)`

Diagram: Math