Handle ln(rational multiple of e) better

Bug: 37486067

In particular, ln(e) is now a rational one.

Test: Unit tests, manual test.
Change-Id: I3cc57a4a84ec6667d3c8554c4fc234f9aa7c2e86
(cherry picked from commit bf2e69ae00d7b70562822769c100c3ddcc928b17)

parent 9223c18a

src/com/android/calculator2/UnifiedReal.java

+3 −0

Original line number	Diff line number	Diff line
		@@ -1011,6 +1011,9 @@ public class UnifiedReal {
		}

		public UnifiedReal ln() {
		if (mCrFactor == CR_E) {
		return new UnifiedReal(mRatFactor, CR_ONE).ln().add(ONE);
		}
		if (isComparable(ZERO)) {
		if (signum() <= 0) {
		throw new ArithmeticException("log(non-positive)");