Name: mf23781 Date: 12/09/97


The behaviour of abs(-0.0) = -0.0 leads to oddities such as

if (1.0 / abs(x) < 0.0) {
}

sometimes being true (when x = -0.0)

The behaviour of abs(-0.0) in JDK 1.1 still appears inconsistent:

The Java code is something like:
public static double abs(double a) {
   return (a < 0) ? -a : a;
}


The behaviour also appears inconsistent in JDK 1.2:

public static double abs(double a) {
    return (a < 0 || a == -0.0D) ? -a : a;
}

If a = +0.0, then a == -0.0D is true (both zeros are equal),
so the statement returns -0.0 for abs(+0.0)


Possible solution is:


   return (a <= 0) ? 0.0 - a : a;

(because 0.0 - (-0.0) = 0.0, 0.0 - (0.0) = 0.0 )

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