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This commit is contained in:
Gilles Sadowski 2021-09-28 21:08:37 +02:00
parent 5460d4d755
commit 6e745db400
1 changed files with 14 additions and 29 deletions
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43
commons-math-legacy-core/src/main/java/org/apache/commons/math4/legacy/core/jdkmath/AccurateMath.java
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@ -32,11 +32,9 @@ import org.apache.commons.math4.legacy.exception.util.LocalizedFormats;
* However, any change to this class should ensure that the current
* accuracy is not lost.
* <p>
* AccurateMath is a drop-in replacement for both Math and StrictMath. This
* means that for any method in Math (say {@code Math.sin(x)} or
* {@code Math.cbrt(y)}), user can directly change the class and use the
* methods as is (using {@code AccurateMath.sin(x)} or {@code AccurateMath.cbrt(y)}
* in the previous example).
* AccurateMath is a drop-in replacement for both Math and StrictMath.
* For example, a call to {@code Math.sin(x)} can be replaced by a call
* to {@code AccurateMath.sin(x)}.
* </p>
* <p>
* AccurateMath speed is achieved by relying heavily on optimizing compilers
@ -45,44 +43,31 @@ import org.apache.commons.math4.legacy.exception.util.LocalizedFormats;
* time does not penalize methods that don't need them.
* </p>
* <p>
* Note that AccurateMath is
* extensively used inside Apache Commons Math, so by calling some algorithms,
* the overhead when the tables need to be initialized will occur
* regardless of the end-user calling AccurateMath methods directly or not.
* Note that AccurateMath is extensively used inside Apache Commons Math,
* so by calling some algorithms, the overhead when the tables need to be
* initialized will occur regardless of the end-user calling AccurateMath
* methods directly or not.
* Performance figures for a specific JVM and hardware can be evaluated by
* running the AccurateMathTestPerformance tests in the test directory of the source
* distribution.
* running the AccurateMathTestPerformance tests in the test directory of
* the source distribution.
* </p>
* <p>
* AccurateMath accuracy should be mostly independent of the JVM as it relies only
* on IEEE-754 basic operations and on embedded tables. Almost all operations
* are accurate to about 0.5 ulp throughout the domain range. This statement,
* of course is only a rough global observed behavior, it is <em>not</em> a
* guarantee for <em>every</em> double numbers input (see William Kahan's <a
* href="http://en.wikipedia.org/wiki/Rounding#The_table-maker.27s_dilemma">Table
* Maker's Dilemma</a>).
* guarantee for <em>every</em> double numbers input (see William Kahan's
* <a href="http://en.wikipedia.org/wiki/Rounding#The_table-maker.27s_dilemma">
* Table Maker's Dilemma</a>).
* </p>
* <p>
* AccurateMath additionally implements the following methods not found in Math/StrictMath:
* AccurateMath implements the following methods not found in Math/StrictMath:
* <ul>
* <li>{@link #asinh(double)}</li>
* <li>{@link #acosh(double)}</li>
* <li>{@link #atanh(double)}</li>
* </ul>
* The following methods are found in Math/StrictMath since 1.6 only, they are provided
* by AccurateMath even in 1.5 Java virtual machines
* <ul>
* <li>{@link #copySign(double, double)}</li>
* <li>{@link #getExponent(double)}</li>
* <li>{@link #nextAfter(double,double)}</li>
* <li>{@link #nextUp(double)}</li>
* <li>{@link #scalb(double, int)}</li>
* <li>{@link #copySign(float, float)}</li>
* <li>{@link #getExponent(float)}</li>
* <li>{@link #nextAfter(float,double)}</li>
* <li>{@link #nextUp(float)}</li>
* <li>{@link #scalb(float, int)}</li>
* </ul>
*
* @since 2.2
*/
public final class AccurateMath {