Fix decimal log(), rename positive_den()
Bug: 20485102
The rational version of base 10 log(0) got into an infinite loop.
Change-Id: Id6263f7244c71260daa124e5eb4eea8592d0e6c7
diff --git a/src/com/android/calculator2/BoundedRational.java b/src/com/android/calculator2/BoundedRational.java
index 54a39f8..04cf86c 100644
--- a/src/com/android/calculator2/BoundedRational.java
+++ b/src/com/android/calculator2/BoundedRational.java
@@ -65,7 +65,7 @@
// Output to user, more expensive, less useful for debugging
// Not internationalized.
public String toNiceString() {
- BoundedRational nicer = reduce().positive_den();
+ BoundedRational nicer = reduce().positiveDen();
String result = nicer.mNum.toString();
if (!nicer.mDen.equals(BigInteger.ONE)) {
result += "/" + nicer.mDen;
@@ -93,7 +93,7 @@
}
// return an equivalent fraction with a positive denominator.
- private BoundedRational positive_den() {
+ private BoundedRational positiveDen() {
if (mDen.compareTo(BigInteger.ZERO) > 0) return this;
return new BoundedRational(mNum.negate(), mDen.negate());
}
@@ -109,7 +109,7 @@
// Return null if none exists.
private BoundedRational maybeReduce() {
if (!tooBig()) return this;
- BoundedRational result = positive_den();
+ BoundedRational result = positiveDen();
if (!result.tooBig()) return this;
result = result.reduce();
if (!result.tooBig()) return this;
@@ -186,7 +186,7 @@
// Return non-null if numerator and denominator are small perfect
// squares.
if (r == null) return null;
- r = r.positive_den().reduce();
+ r = r.positiveDen().reduce();
if (r.mNum.compareTo(BigInteger.ZERO) < 0) {
throw new ArithmeticException("sqrt(negative)");
}
@@ -384,19 +384,20 @@
return new BoundedRational(1);
}
if (base == null) return null;
- exp = exp.reduce().positive_den();
+ exp = exp.reduce().positiveDen();
if (!exp.mDen.equals(BigInteger.ONE)) return null;
return base.pow(exp.mNum);
}
public static BoundedRational ln(BoundedRational r) {
- if (r != null && r.signum() < 0) {
- throw new ArithmeticException("log(negative)");
+ if (r != null && r.signum() <= 0) {
+ throw new ArithmeticException("log(non-positive)");
}
return map1to0(r);
}
// Return the base 10 log of n, if n is a power of 10, -1 otherwise.
+ // n must be positive.
private static long b10Log(BigInteger n) {
// This algorithm is very naive, but we doubt it matters.
long count = 0;
@@ -412,10 +413,10 @@
public static BoundedRational log(BoundedRational r) {
if (r == null) return null;
- if (r.signum() < 0) {
- throw new ArithmeticException("log(negative)");
+ if (r.signum() <= 0) {
+ throw new ArithmeticException("log(non-positive)");
}
- r = r.reduce();
+ r = r.reduce().positiveDen();
if (r == null) return null;
if (r.mDen.equals(BigInteger.ONE)) {
long log = b10Log(r.mNum);