While writing a function to return a the max vector late in evening I encountered the following assertion error for the code below. Just went home, thinking i am seeing something wrong since its late :-)
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The shouldReturnMaxVector below fails with the following error
Expected: [2 .0, -6 .0f, -5 .0f]
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@Test
public void shouldReturnMaxVector() throws Exception {
float[] max = max(new float[]{Float.MIN_VALUE, Float.MIN_VALUE, Float.MIN_VALUE}, new float[]{2, -6, -5});
assertThat(max, is(new float[]{2, -6, -5}));
}
public static float[] max(float[] v1, float[] v2) {
return findByCompare(v1, v2, (x, y) -> x > y);
}
public static float[] findByCompare(float[] v1, float[] v2,
BiFunction selector) {
float[] result = new float[v1.length];
for (int i = 0; i < v1.length; i++) {
result[i] = selector.apply(v1[i], v2[i]) ? v1[i] : v2[i];
}
return result;
}
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Later i realized, Float.MIN_VALUE is not negative. The following stack overflow answer (https://bit.ly/2J6tKbI) provides a good explanation for the same.
Below is the answer from SO
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The IEEE 754 format has one bit reserved for the sign and the remaining bits representing the magnitude. This means that it is "symmetrical" around origo (as opposed to the Integer values, which have one more negative value). Thus the minimum value is simply the same as the maximum value, with the sign-bit changed, so yes,-Double.MAX_VALUEis the smallest possible actual number you can represent with adouble.I suppose theDouble.MAX_VALUEshould be seen as maximum magnitude, in which case it actually makes sense to simply write-Double.MAX_VALUE. It also explains whyDouble.MIN_VALUEis the least positive value (since that represents the least possible magnitude).But sure, I agree that the naming is a bit misleading. Being used to the meaningInteger.MIN_VALUE, I too was a bit surprised when I read thatDouble.MIN_VALUEwas the smallest absolute value that could be represented. Perhaps they thought it was superfluous to have a constant representing the least possible value as it is simply a-away fromMAX_VALUE:-)(Note, there is alsoDouble.NEGATIVE_INFINITYbut I'm disregarding from this, as it is to be seen as a "special case" and does not in fact represent any actual number.) Here is a good text on the subject.
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