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ericbarnhill pushed a commit to branch fraction-dev
in repository https://gitbox.apache.org/repos/asf/commons-numbers.git
The following commit(s) were added to refs/heads/fraction-dev by this push:
new 4304d1e NUMBERS-91: Fixes to BigFraction related Formatting classes
4304d1e is described below
commit 4304d1e0d195b086e19edcc7f963c097d87ce3f6
Author: Eric Barnhill <ericbarnh...@protonmail.ch>
AuthorDate: Fri Jan 18 14:44:32 2019 -0800
NUMBERS-91: Fixes to BigFraction related Formatting classes
---
.../commons/numbers/fraction/BigFraction.java | 25 ++++++++++++++++++++++
.../numbers/fraction/BigFractionFormat.java | 8 +++----
.../numbers/fraction/ProperBigFractionFormat.java | 4 ++--
3 files changed, 31 insertions(+), 6 deletions(-)
diff --git
a/commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/BigFraction.java
b/commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/BigFraction.java
index 3cecc73..8c1d51d 100644
---
a/commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/BigFraction.java
+++
b/commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/BigFraction.java
@@ -116,6 +116,31 @@ public class BigFraction
/**
* Create a fraction given the double value.
* <p>
+ * This factory method behaves <em>differently</em> from
+ * {@link #from(double, double, int)}. It converts the double value
+ * exactly, considering its internal bits representation. This works for
all
+ * values except NaN and infinities and does not requires any loop or
+ * convergence threshold.
+ * </p>
+ * <p>
+ * Since this conversion is exact and since double numbers are sometimes
+ * approximated, the fraction created may seem strange in some cases. For
example,
+ * calling <code>new BigFraction(1.0 / 3.0)</code> does <em>not</em> create
+ * the fraction 1/3, but the fraction 6004799503160661 / 18014398509481984
+ * because the double number passed to the constructor is not exactly 1/3
+ * (this number cannot be stored exactly in IEEE754).
+ * </p>
+ * @see #BigFraction(double, double, int)
+ * @param value the double value to convert to a fraction.
+ * @exception IllegalArgumentException if value is NaN or infinite
+ */
+ public static BigFraction from(final double value) throws
IllegalArgumentException {
+ return new BigFraction(value);
+ }
+
+ /**
+ * Create a fraction given the double value.
+ * <p>
* This constructor behaves <em>differently</em> from
* {@link #BigFraction(double, double, int)}. It converts the double value
* exactly, considering its internal bits representation. This works for
all
diff --git
a/commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/BigFractionFormat.java
b/commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/BigFractionFormat.java
index 822e6a2..ac302c2 100644
---
a/commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/BigFractionFormat.java
+++
b/commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/BigFractionFormat.java
@@ -163,9 +163,9 @@ public class BigFractionFormat extends AbstractFormat
implements Serializable {
if (obj instanceof BigFraction) {
ret = format((BigFraction) obj, toAppendTo, pos);
} else if (obj instanceof BigInteger) {
- ret = format(new BigFraction((BigInteger) obj), toAppendTo, pos);
+ ret = format(BigFraction.of((BigInteger) obj), toAppendTo, pos);
} else if (obj instanceof Number) {
- ret = format(new BigFraction(((Number) obj).doubleValue()),
+ ret = format(BigFraction.from(((Number) obj).doubleValue()),
toAppendTo, pos);
} else {
throw new IllegalArgumentException("cannot format given object as
a fraction number");
@@ -222,7 +222,7 @@ public class BigFractionFormat extends AbstractFormat
implements Serializable {
case 0 :
// no '/'
// return num as a BigFraction
- return new BigFraction(num);
+ return BigFraction.of(num);
case '/' :
// found '/', continue parsing denominator
break;
@@ -248,7 +248,7 @@ public class BigFractionFormat extends AbstractFormat
implements Serializable {
return null;
}
- return new BigFraction(num, den);
+ return BigFraction.of(num, den);
}
/**
diff --git
a/commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/ProperBigFractionFormat.java
b/commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/ProperBigFractionFormat.java
index 7460d0e..655e6d7 100644
---
a/commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/ProperBigFractionFormat.java
+++
b/commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/ProperBigFractionFormat.java
@@ -174,7 +174,7 @@ public class ProperBigFractionFormat extends
BigFractionFormat {
case 0 :
// no '/'
// return num as a BigFraction
- return new BigFraction(num);
+ return BigFraction.of(num);
case '/' :
// found '/', continue parsing denominator
break;
@@ -215,7 +215,7 @@ public class ProperBigFractionFormat extends
BigFractionFormat {
num = num.negate();
}
- return new BigFraction(num, den);
+ return BigFraction.of(num, den);
}
