/**
* 1d inverse discrete fourier transform see matlab's fft2 for more examples. Note that this will
* throw an exception if the input isn't a vector
*
* @param inputC the input to transform
* @return the inverse fourier transform of the passed in input
*/
public static ComplexNDArray complexInverseDisceteFourierTransform1d(ComplexNDArray inputC) {
if (inputC.shape().length != 1)
throw new IllegalArgumentException("Illegal input: Must be a vector");
double len = MatrixUtil.length(inputC);
ComplexDouble c2 = new ComplexDouble(0, -2).muli(FastMath.PI).divi(len);
ComplexDoubleMatrix range = MatrixUtil.complexRangeVector(0, len);
ComplexDoubleMatrix div2 = range.transpose().mul(c2);
ComplexDoubleMatrix div3 = range.mmul(div2).negi();
ComplexDoubleMatrix matrix = exp(div3).div(len);
ComplexDoubleMatrix complexRet = matrix.mmul(inputC);
return ComplexNDArray.wrap(inputC, complexRet);
}
/**
* 1d inverse discrete fourier transform see matlab's fft2 for more examples. Note that this will
* throw an exception if the input isn't a vector
*
* @param inputC the input to transform
* @return the inverse fourier transform of the passed in input
*/
public static ComplexFloatMatrix complexInverseDisceteFourierTransform1d(
ComplexFloatMatrix inputC) {
if (inputC.rows != 1 && inputC.columns != 1)
throw new IllegalArgumentException("Illegal input: Must be a vector");
float len = MatrixUtil.length(inputC);
ComplexFloat c2 = new ComplexFloat(0, -2).muli((float) FastMath.PI).divi(len);
ComplexFloatMatrix range = MatrixUtil.complexRangeVector(0, (int) len);
ComplexFloatMatrix div2 = range.transpose().mul(c2);
ComplexFloatMatrix div3 = range.mmul(div2).negi();
ComplexFloatMatrix matrix = exp(div3).div(len);
ComplexFloatMatrix complexRet =
inputC.isRowVector() ? matrix.mmul(inputC) : inputC.mmul(matrix);
return complexRet;
}
