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Plan.java
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Fri, Dec 20, 00:54

Plan.java
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package jfftw.complex;
/**
* Corresponds to an FFTW <code>fftw_plan</code> (plan for complex one
* dimensional transforms) structure.
*
* A plan is a choice of algorithm to optimally compute transforms for a given
* size of data. Once you have a <code>Plan</code> you can use it to compute a
* number of transforms for data of the same size. Creating a plan results in
* collection of much information, that will be reused at succeding creation of
* plans.
*
* <p>
* We represent a complex array of length N as a real (<code>float</code>) array
* of length 2*N, where the <i>(2*i)</i>th element (of the real array)
* corresponds to the real part of the <i>i</i>th element (of the complex array)
* and the <i>(2*i+1)</i>th element (of the real array) corresponds to the
* imaginary part of the <i>i</i>th element (of the complex array).
* <p>
* For more information see the <a href="http://www.fftw.org">FFTW</a>
* documentation. The FFTW library is work of MIT. The jfftw package is work of
* Daniel Darabos
*
* (<a href="mailto:cyhawk@sch.bme.hu">cyhawk@sch.bme.hu</a>).
*
* Both have GPL licenses.
*/
public class Plan implements jfftw.Plan {
/**
* I store <code>fftwnd_plan</code> (the pointer) in this byte array. It is
* ugly, but I don't know the proper way.
*/
private byte plan[];
/**
* Constructs a <code>Plan</code> for the given length <code>n</code>,
* direction <code>dir</code>, initialization <code>flags</code> and actual
* input/output arrays. The contents of the arrays are not used (they can be
* uninitialized) but will be destroyed.
*
* <p>
* (See FFTW documentation on <code>fftw_create_plan_specific</code> for
* more insight.)
*
* @param dir
* One of {@link #FORWARD} and {@link #BACKWARD}.
* @param flags
* One of {@link #ESTIMATE} (default) and {@link #MEASURE}
* optionally <code>OR</code>'ed with {@link #USE_WISDOM},
* {@link #IN_PLACE} and {@link #READONLY}. Any other flag
* constants from <code>fftw.h</code> might be working, but jfftw
* has not been tested with them.
* @throws RuntimeException
* if the float type of Java is not of the same size as
* <code>fftw_real</code>. (If this is the case, the library
* will need to be modified and recompiled. If FFTW was not
* compiled with
*
* <code>FFTW_ENABLE_FLOAT</code> all float types should be
* changed to double in the Java and native source -- or
* recompile FFTW with <code>FFTW_ENABLE_FLOAT</code>.)
*/
public Plan(int n, int dir, int flags, float[] in, int idist, float[] out, int odist) {
if (dir != FORWARD && dir != BACKWARD)
throw new IllegalArgumentException("dir must be either FORWARD or BACKWARD");
createPlanSpecific(n, dir, flags, in, idist, out, odist);
}
/**
* Constructs a <code>Plan</code> for the given length <code>n</code>,
* direction <code>dir</code> and initialization <code>flags</code>.
*
* @param dir
* One of {@link #FORWARD} and {@link #BACKWARD}.
* @param flags
* One of {@link #ESTIMATE} (default) and {@link #MEASURE}
* optionally <code>OR</code>'ed with {@link #USE_WISDOM},
* {@link #IN_PLACE} and {@link #READONLY}. Any other flag
* constants from <code>fftw.h</code> might be working, but jfftw
* has not been tested with them.
* @throws RuntimeException
* if the float type of Java is not of the same size as
* <code>fftw_real</code>. (If this is the case, the library
* will need to be modified and recompiled. If FFTW was not
* compiled with
*
* <code>FFTW_ENABLE_FLOAT</code> all float types should be
* changed to double in the Java and native source -- or
* recompile FFTW with <code>FFTW_ENABLE_FLOAT</code>.)
*/
public Plan(int n, int dir, int flags) {
if (dir != FORWARD && dir != BACKWARD)
throw new IllegalArgumentException("dir must be either FORWARD or BACKWARD");
createPlan(n, dir, flags);
}
/**
* Constructs a <code>Plan</code> for the given length <code>n</code> and
* direction <code>dir</code> based on estimations (see
* <code>ESTIMATE</code>). Same as
*
* <code>Plan( dim, dir, Plan.ESTIMATE )</code>.
*
* @param dir
* One of {@link #FORWARD} and {@link #BACKWARD}.
* @throws RuntimeException
* if the float type of Java is not of the same size as
* <code>fftw_real</code>. (If this is the case, the library
* will need to be modified and recompiled. If FFTW was not
* compiled with
*
* <code>FFTW_ENABLE_FLOAT</code> all float types should be
* changed to double in the Java and native source -- or
* recompile FFTW with <code>FFTW_ENABLE_FLOAT</code>.)
*/
public Plan(int n, int dir) {
if (dir != FORWARD && dir != BACKWARD)
throw new IllegalArgumentException("dir must be either FORWARD or BACKWARD");
createPlan(n, dir, ESTIMATE);
}
/**
* Constructs a forward (see <code>FORWARD</code>)
*
* <code>Plan</code> for the given length <code>n</code> based on
*
* estimations (see <code>ESTIMATE</code>). Same as
*
* <code>Plan( n, Plan.FORWARD, Plan.ESTIMATE )</code>.
*
* @throws RuntimeException
* if the float type of Java is not of the same size as
* <code>fftw_real</code>. (If this is the case, the library
* will need to be modified and recompiled. If FFTW was not
* compiled with
*
* <code>FFTW_ENABLE_FLOAT</code> all float types should be
* changed to double in the Java and native source -- or
* recompile FFTW with <code>FFTW_ENABLE_FLOAT</code>.)
*/
public Plan(int n) {
createPlan(n, FORWARD, ESTIMATE);
}
/**
* Destroys the <code>fftwnd_plan</code> structure.
*/
protected void finalize() {
destroyPlan();
}
private native void createPlan(int n, int dir, int flags);
private native void createPlanSpecific(int n, int dir, int flags, float[] in, int idist, float[] out, int odist);
private native void destroyPlan();
/**
* Calculates the Fourier transform of <code>in</code>.
*
* <p>
* (See FFTW documentation for details. The function behind it is
* <code>fftw_one</code>.)
*
* @throws IndexOutOfBoundsException
* if <code>in</code> is not float the size that was passed to
* the constructor.
*/
public native float[] transform(float[] in);
/**
* Calculates multiple Fourier transforms.
*
* <p>
* (See FFTW documentation for details. The function behind it is
* <code>fftw</code>, the arguments are mapped to <code>fftw</code>'s
* arguments of the same name.)
*
* @throws IndexOutOfBoundsException
* if <code>in</code> or <code>out</code> are not of the proper
* size.
*/
public native void transform(int howmany, float[] in, int istride, int idist, float[] out, int ostride, int odist);
static {
// System.loadLibrary("FFTWJNI");
// FFTWLoader.run();
}
}

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