tf.keras.ops.irfft

Inverse real-valued Fast Fourier transform along the last axis.

tf.keras.ops.irfft(
    x, fft_length=None
)

Computes the inverse 1D Discrete Fourier Transform of a real-valued signal over the inner-most dimension of input.

The inner-most dimension of the input is assumed to be the result of RFFT: the fft_length / 2 + 1 unique components of the DFT of a real-valued signal. If fft_length is not provided, it is computed from the size of the inner-most dimension of the input (fft_length = 2 * (inner - 1)). If the FFT length used to compute is odd, it should be provided since it cannot be inferred properly.

Along the axis IRFFT is computed on, if fft_length / 2 + 1 is smaller than the corresponding dimension of the input, the dimension is cropped. If it is larger, the dimension is padded with zeros.

x Tuple of the real and imaginary parts of the input tensor. Both tensors in the tuple should be of floating type.
fft_length An integer representing the number of the fft length. If not specified, it is inferred from the length of the last axis of x. Defaults to None.

A tensor containing the inverse real-valued Fast Fourier Transform along the last axis of x.

Examples:

real = keras.ops.convert_to_tensor([0.0, 1.0, 2.0, 3.0, 4.0])
imag = keras.ops.convert_to_tensor([0.0, 1.0, 2.0, 3.0, 4.0])
irfft((real, imag))
array([0.66666667, -0.9106836, 0.24401694])

irfft(rfft(real, 5), 5)
array([0.0, 1.0, 2.0, 3.0, 4.0])