public void testLog2Accuracy() {
for (double d : POSITIVE_FINITE_DOUBLE_CANDIDATES) {
double dmLog2 = DoubleMath.log2(d);
double trueLog2 = trueLog2(d);
assertTrue(Math.abs(dmLog2 - trueLog2) <= Math.ulp(trueLog2));
}
}
public void testFactorial() {
for (int i = 0; i <= DoubleMath.MAX_FACTORIAL; i++) {
double actual = BigIntegerMath.factorial(i).doubleValue();
double result = DoubleMath.factorial(i);
assertEquals(actual, result, Math.ulp(actual));
}
}
public void testRoundLog2Half() {
// We don't expect perfect rounding accuracy.
for (int exp : asList(-1022, -50, -1, 0, 1, 2, 3, 4, 100, 1022, 1023)) {
for (RoundingMode mode : asList(HALF_EVEN, HALF_UP, HALF_DOWN)) {
double x = Math.scalb(Math.sqrt(2) + 0.001, exp);
double y = Math.scalb(Math.sqrt(2) - 0.001, exp);
if (exp < 0) {
assertEquals(exp + 1, DoubleMath.log2(x, mode));
assertEquals(exp, DoubleMath.log2(y, mode));
} else {
assertEquals(exp + 1, DoubleMath.log2(x, mode));
assertEquals(exp, DoubleMath.log2(y, mode));
}
}
}
}
public void testFuzzyEqualsFinite() {
for (double a : FINITE_DOUBLE_CANDIDATES) {
for (double b : FINITE_DOUBLE_CANDIDATES) {
for (double tolerance : FINITE_TOLERANCE_CANDIDATES) {
assertEquals(Math.abs(a - b) <= tolerance, DoubleMath.fuzzyEquals(a, b, tolerance));
}
}
}
}
public void testRoundLog2Exact() {
for (double x : POSITIVE_FINITE_DOUBLE_CANDIDATES) {
boolean isPowerOfTwo = StrictMath.pow(2.0, DoubleMath.log2(x, FLOOR)) == x;
try {
int log2 = DoubleMath.log2(x, UNNECESSARY);
assertEquals(x, Math.scalb(1.0, log2));
assertTrue(isPowerOfTwo);
} catch (ArithmeticException e) {
assertFalse(isPowerOfTwo);
}
}
}