# rfft¶

paddle.fft. rfft ( x, n=None, axis=- 1, norm='backward', name=None ) [source]

The one dimensional FFT for real input.

This function computes the one dimensional n-point discrete Fourier Transform (DFT) of a real-valued tensor by means of an efficient algorithm called the Fast Fourier Transform (FFT).

When the DFT is computed for purely real input, the output is Hermitian-symmetric. This function does not compute the negative frequency terms, and the length of the transformed axis of the output is therefore `n//2 + 1`.

Parameters
• x (Tensor) – Real-valued input tensor

• n (int, optional) – Number of points along transformation axis in the input to use. If n is smaller than the length of the input, the input is cropped. If it is larger, the input is padded with zeros. If n is not given, the length of the input along the axis specified by axis is used.

• axis (int, optional) – Axis over which to compute the FFT. Default value is last axis.

• norm (str, optional) –

Normalization mode, indicates which direction of the forward/backward pair of transforms is scaled and with what normalization factor. Include {“backward”, “ortho”, “forward”}, default value is “backward”.

• ”backward”: The factor of forward direction and backward direction are `1` and `1/n` respectively;

• ”forward”: The factor of forward direction and backward direction are `1/n` and `1` respectively;

• ”ortho”: The factor of forward direction and backword direction are both `1/sqrt(n)`.

Where `n` is the multiplication of each element in `s` .

• name (str, optional) – The default value is None. Normally there is no need for user to set this property. For more information, please refer to Name .

Returns

complex tensor

Return type

out(Tensor)

Examples:

```import paddle

x = paddle.to_tensor([0.0, 1.0, 0.0, 0.0])