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The S-Space Package is a Natural Language Processing library for
distributional semantics representations. Distributional semantics
representations model the meaning of words, phrases, and sentences as high
dimensional vectors or probability distributions. The library includes common
algorithms such as Latent Semantic Analysis, Random Indexing, and Latent
Dirichlet Allocation. The S-Space package also includes software libraries
for matrices, vectors, graphs, and numerous clustering
algorithms.
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package jnt.FFT;
/** Computes the FFT of 2 dimensional complex, single precision data.
* The data is stored in a 1-dimensional array in Row-Major order.
* The physical layout in the array data, of the mathematical data d[i,j] is as follows:
*
* Re(d[i,j]) = data[i*rowspan + 2*j]
* Im(d[i,j]) = data[i*rowspan + 2*j + 1]
*
* where rowspan must be at least 2*ncols (it defaults to 2*ncols).
* The transformed data is returned in the original data array in
* wrap-around order along each dimension.
*
* @author Bruce R. Miller [email protected]
* @author Contribution of the National Institute of Standards and Technology,
* @author not subject to copyright.
*/
public class ComplexFloat2DFFT {
int nrows;
int ncols;
ComplexFloatFFT rowFFT, colFFT;
/** Create an FFT for transforming nrows*ncols points of Complex, double precision
* data. */
public ComplexFloat2DFFT(int nrows, int ncols) {
this.nrows = nrows;
this.ncols = ncols;
rowFFT = new ComplexFloatFFT_Mixed(ncols);
colFFT = (nrows == ncols ? rowFFT : new ComplexFloatFFT_Mixed(nrows));
}
protected void checkData(float data[], int rowspan){
if (rowspan < 2*ncols)
throw new IllegalArgumentException("The row span "+rowspan+
"is shorter than the row length "+2*ncols);
if (nrows*rowspan > data.length)
throw new IllegalArgumentException("The data array is too small for "+
nrows+"x"+rowspan+" data.length="+data.length);}
/** Compute the Fast Fourier Transform of data leaving the result in data.
* The array data must be dimensioned (at least) 2*nrows*ncols, consisting of
* alternating real and imaginary parts. */
public void transform(float data[]) {
transform(data,2*ncols); }
/** Compute the Fast Fourier Transform of data leaving the result in data.
* The array data must be dimensioned (at least) 2*nrows*ncols, consisting of
* alternating real and imaginary parts. */
public void transform(float data[], int rowspan) {
checkData(data,rowspan);
for(int i=0; iwraparound format */
public float[] toWraparoundOrder(float data[]){
return data; }
/** Return data in wraparound order.
* rowspan is used to traverse data; the new array is in
* packed (rowspan = 2*ncols) format.
* @see wraparound format */
public float[] toWraparoundOrder(float data[], int rowspan){
if (rowspan == 2*ncols) return data;
float newdata[] = new float[2*nrows*ncols];
for(int i=0; i