/**
* Discrete fourier transform 2d
*
* @param input the input to transform
* @param rows the number of rows in the transformed output matrix
* @param cols the number of columns in the transformed output matrix
* @return the discrete fourier transform of the input
*/
public static ComplexFloatMatrix complexDisceteFourierTransform(
FloatMatrix input, int rows, int cols) {
ComplexFloatMatrix base;
// pad
if (input.rows < rows || input.columns < cols)
base = MatrixUtil.complexPadWithZeros(input, rows, cols);
// truncation
else if (input.rows > rows || input.columns > cols) {
base = new ComplexFloatMatrix(input);
base =
base.get(
MatrixUtil.toIndices(RangeUtils.interval(0, rows)),
MatrixUtil.toIndices(RangeUtils.interval(0, cols)));
} else base = new ComplexFloatMatrix(input);
ComplexFloatMatrix temp = new ComplexFloatMatrix(base.rows, base.columns);
ComplexFloatMatrix ret = new ComplexFloatMatrix(base.rows, base.columns);
for (int i = 0; i < base.columns; i++) {
ComplexFloatMatrix column = base.getColumn(i);
temp.putColumn(i, complexDiscreteFourierTransform1d(column));
}
for (int i = 0; i < ret.rows; i++) {
ComplexFloatMatrix row = temp.getRow(i);
ret.putRow(i, complexDiscreteFourierTransform1d(row));
}
return ret;
}
/**
* Discrete fourier transform 2d
*
* @param input the input to transform
* @param shape the shape of the output matrix
* @return the discrete fourier transform of the input
*/
public static ComplexDoubleMatrix complexDisceteFourierTransform(NDArray input, int[] shape) {
ComplexNDArray base;
// pad
if (ArrayUtil.anyLess(input.shape(), shape))
base = MatrixUtil.complexPadWithZeros(input, shape);
// truncation
else if (ArrayUtil.anyMore(input.shape(), shape)) {
base = new ComplexNDArray(shape);
for (int i = 0; i < ArrayUtil.prod(shape); i++) base.put(i, input.get(i));
} else base = new ComplexNDArray(input);
ComplexNDArray temp = new ComplexNDArray(shape);
ComplexNDArray ret = new ComplexNDArray(shape);
for (int i = 0; i < base.columns; i++) {
ComplexDoubleMatrix column = base.getColumn(i);
temp.putColumn(i, complexDiscreteFourierTransform1d(column));
}
for (int i = 0; i < ret.rows; i++) {
ComplexDoubleMatrix row = temp.getRow(i);
ret.putRow(i, complexDiscreteFourierTransform1d(row));
}
return ret;
}