FloatEqualThreshhold broken ?

I'm first going to ask you guys to confirm this before marking this as a bug. But shouldn't this FloatEqualThreshold(8.742278e-08, 0, 1e-4) return true ? (because it doesn't)

Ok so i looked up where you guys found the implementation for this function and the original author thinks that it's ok that pure 0 isn't equal to something very very close to zero.

    assertFalse(nearlyEqual(0.00000001f, 0.0f));
    assertFalse(nearlyEqual(0.0f, 0.00000001f));
    assertFalse(nearlyEqual(-0.00000001f, 0.0f));
    assertFalse(nearlyEqual(0.0f, -0.00000001f));

Personally I can't agree with that but I don't want to change the lib if you guys think so.

UPDATE: ok i digged in deeper and realised that epsilon passed to FloatEqualThreshold isnt the max difference between a and b. This should be mentioned and it should be clear how it scales with numbers.

Also, the declaration in java is

public static boolean nearlyEqual(float a, float b, float epsilon) {
    final float absA = Math.abs(a);
    final float absB = Math.abs(b);
    final float diff = Math.abs(a - b);

    if (a == b) { // shortcut, handles infinities
        return true;
    } else if (a == 0 || b == 0 || diff < Float.MIN_NORMAL) {
        // a or b is zero or both are extremely close to it
        // relative error is less meaningful here
        return diff < (epsilon * Float.MIN_NORMAL);
    } else { // use relative error
        return diff / Math.min((absA + absB), Float.MAX_VALUE) < epsilon;
    }
}

while ours is

func FloatEqualThreshold(a, b, epsilon float32) bool {
    if a == b { // Handles the case of inf or shortcuts the loop when no significant error has     accumulated
        return true
    }

    diff := Abs(a - b)
    if a*b == 0 || diff < MinNormal { // If a or b are 0 or both are extremely close to it
        return diff < epsilon*epsilon
    }

    // Else compare difference
    return diff/(Abs(a)+Abs(b)) < epsilon
}

Any reason we do epsilon*epsilon instead of epsilon*MinNormal?

We should add a function that takes a target float, a "biggest difference" and returns a epsilon

[emidoots]

@hydroflame I haven't read everything here -- but you may be looking for relative equality, e.g. https://github.com/azul3d/lmath/blob/master/math.go#L12-L22 (http://realtimecollisiondetection.net/blog/?p=89)

Yeah we still need a clearer documentation