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Javadoc (MATH-677). 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1227015 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Sebastien Brisard 2012-01-04 01:31:23 +00:00
parent 2689ee367b
commit 7f6912730e
1 changed files with 20 additions and 14 deletions
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34
src/main/java/org/apache/commons/math/transform/FastFourierTransformer.java
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@ -266,13 +266,14 @@ public class FastFourierTransformer implements Serializable {
} }
/** /**
* Perform the base-4 Cooley-Tukey FFT algorithm (including inverse). * Returns the FFT of the specified real data set. Performs the base-4
* Cooley-Tukey FFT algorithm.
* *
* @param f the real data array to be transformed * @param f the real data array to be transformed
* @param isInverse the indicator of forward or inverse transform * @param isInverse {@code true} if inverse transform is to be carried out
* @return the complex transformed array * @return the complex transformed array
* @throws IllegalArgumentException if any parameters are invalid * @throws MathIllegalArgumentException if the length of the data array is
* @throws MathIllegalArgumentException if array length is not a power of 2 * not a power of two
*/ */
protected Complex[] fft(double[] f, boolean isInverse) protected Complex[] fft(double[] f, boolean isInverse)
throws MathIllegalArgumentException { throws MathIllegalArgumentException {
@ -313,12 +314,13 @@ public class FastFourierTransformer implements Serializable {
} }
/** /**
* Perform the base-4 Cooley-Tukey FFT algorithm (including inverse). * Returns the FFT of the specified complex data set. Performs the base-4
* Cooley-Tukey FFT algorithm.
* *
* @param data the complex data array to be transformed * @param data the complex data array to be transformed
* @return the complex transformed array * @return the complex transformed array
* @throws IllegalArgumentException if any parameters are invalid * @throws MathIllegalArgumentException if the length of the data array is
* @throws MathIllegalArgumentException if array length is not a power of 2 * not a power of two
*/ */
protected Complex[] fft(Complex[] data) protected Complex[] fft(Complex[] data)
throws MathIllegalArgumentException { throws MathIllegalArgumentException {
@ -390,12 +392,16 @@ public class FastFourierTransformer implements Serializable {
} }
/** /**
* Sample the given univariate real function on the given interval.
* <p> * <p>
* The interval is divided equally into N sections and sample points * Sample the given univariate real function on the given interval.
* are taken from min to max-(max-min)/N. Usually f(x) is periodic * </p>
* such that f(min) = f(max) (note max is not sampled), but we don't * <p>
* require that.</p> * The interval is divided equally into {@code n} sections and sample points
* are taken from {@code min} to {@code max - (max - min) / N}. Usually
* {@code f(x)} is periodic such that {@code f(min) = f(max)} (note that
* {@code max} is not sampled), but this condition is not required by the
* present method.
* </p>
* *
* @param f the function to be sampled * @param f the function to be sampled
* @param min the (inclusive) lower bound for the interval * @param min the (inclusive) lower bound for the interval
@ -460,10 +466,10 @@ public class FastFourierTransformer implements Serializable {
} }
/** /**
* Returns true if the argument is power of 2. * Returns true if the argument is a power of 2.
* *
* @param n the number to test * @param n the number to test
* @return true if the argument is power of 2 * @return true if the argument is a power of 2
*/ */
public static boolean isPowerOf2(long n) { public static boolean isPowerOf2(long n) {
return (n > 0) && ((n & (n - 1)) == 0); return (n > 0) && ((n & (n - 1)) == 0);