public Rational add(Rational b) {
if (zero(num)) return b;
else if (zero(b.num)) return this;
Rational rv = new Rational(this);
rv.addEq(b);
return rv;
}
public static Rational sum(Iterable<Rational> list) {
Rational sum = ZERO;
for (Rational rat : list) {
sum.addEq(rat);
}
return sum;
}
public Rational reciprocate() {
if (zero(num)) throw new ArithmeticException("Divide by zero");
Rational rv = new Rational(this);
rv.flip();
if (negative(den)) {
rv.num = rv.num.negate();
rv.den = rv.den.negate();
}
return rv;
}
// TODO: put this somewhere else...
public static void printRow(
String name, Rational value, ColumnTextWriter colpp, boolean excludeZero) {
if (!value.isZero() || !excludeZero) {
colpp.writeCol(name);
colpp.writeCol(value.toString());
if (!BigIntegerUtils.one(value.den)) {
colpp.writeCol(String.format("%.3f", value.doubleValue()));
}
colpp.endRow();
}
}
public int compareTo(Rational other) {
if (num.equals(other.num) && den.equals(other.den)) return 0;
// see if it is a num only compare...
if (den.equals(other.den)) return (greater(other.num, this.num)) ? -1 : 1;
// check signs...
if ((zero(num) || negative(num)) && positive(other.num)) return -1;
else if (positive(num) && (zero(other.num) || negative(other.num))) return 1;
BigInteger c1 = new BigInteger(other.num.toString());
BigInteger c2 = new BigInteger(other.den.toString());
Rational c = new Rational(c1, c2);
c = c.negate();
c.addEq(this);
return (c.isZero() ? 0 : (negative(c.num) ? -1 : 1));
}
public static Rational valueOf(BigDecimal x) {
BigInteger num = x.unscaledValue();
BigInteger den = BigInteger.ONE;
int scale = x.scale();
while (scale > 0) {
den = den.multiply(BigInteger.TEN);
--scale;
}
while (scale < 0) {
num = num.multiply(BigInteger.TEN);
++scale;
}
Rational rv = new Rational(num, den);
rv.reduce();
return rv;
}
public static Rational[] probVector(int length, Random prng) {
if (length == 0) return new Rational[] {};
else if (length == 1) return new Rational[] {Rational.ONE};
double dProb = prng.nextDouble();
Rational probA = Rational.valueOf(dProb);
Rational probB = Rational.valueOf(1 - dProb);
if (length == 2) {
return new Rational[] {probA, probB};
} else {
Rational[] a = probVector(length / 2, prng);
Rational[] b = probVector((length + 1) / 2, prng);
Rational[] c = new Rational[a.length + b.length];
for (int i = 0; i < a.length; ++i) {
c[i] = a[i].multiply(probA);
}
for (int i = 0; i < b.length; ++i) {
c[a.length + i] = b[i].multiply(probB);
}
return c;
}
}
public Rational divide(Rational b) {
Rational rv = new Rational(b);
rv.flip();
rv.mulEq(this);
return rv;
}
public Rational multiply(Rational b) {
if (zero(num) || zero(b.num)) return ZERO;
Rational rv = new Rational(this);
rv.mulEq(b);
return rv;
}
public Rational subtract(long b) {
if (b == 0) return this;
Rational c = new Rational(-b);
c.addEq(this);
return c;
}
public Rational subtract(Rational b) {
if (zero(b.num)) return this;
Rational c = b.negate();
if (!zero(num)) c.addEq(this);
return c;
}
public Rational add(long b) {
if (b == 0) return this;
Rational rv = new Rational(b);
rv.addEq(this);
return rv;
}