Enum FftNormalization 

pub enum FftNormalization {
    None,
    Backward,
    Ortho,
    Forward,
}

Normalization mode for FFT

Default: Backward

The default normalization mode is Backward, which matches NumPy’s numpy.fft behavior. This means:

• Forward FFT: no normalization (factor = 1)
• Inverse FFT: divide by N (factor = 1/N)

This ensures that ifft(fft(x)) == x (roundtrip identity).

Comparison Table

Mode	Forward Factor	Inverse Factor	Roundtrip
None	1	1	ifft(fft(x)) = N*x
Backward	1	1/N	ifft(fft(x)) = x
Ortho	1/√N	1/√N	ifft(fft(x)) = x
Forward	1/N	1	ifft(fft(x)) = x

Variants

None

No normalization (forward: 1, inverse: 1)

Warning: Roundtrip produces N * x. Use when you need unnormalized raw FFT output, such as for convolution or custom post-processing.

Backward

Normalize inverse by 1/N (forward: 1, inverse: 1/N)

Default mode. Matches numpy.fft behavior. Roundtrip: ifft(fft(x)) == x

Ortho

Normalize both by 1/sqrt(N) (forward: 1/√N, inverse: 1/√N)

Makes FFT and IFFT symmetric. Preserves Parseval’s theorem: sum(|x|²) == sum(|X|²) (energy conservation). Useful for signal processing where symmetry matters.

Forward

Normalize forward by 1/N (forward: 1/N, inverse: 1)

Opposite of Backward. Roundtrip: ifft(fft(x)) == x

Implementations

impl FftNormalization

pub fn factor(self, direction: FftDirection, n: usize) -> f64

Get the normalization factor for a given direction and size

Trait Implementations

impl Clone for FftNormalization

fn clone(&self) -> FftNormalization

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FftNormalization

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for FftNormalization

fn default() -> FftNormalization

Returns the “default value” for a type.

impl PartialEq for FftNormalization

fn eq(&self, other: &FftNormalization) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for FftNormalization

impl Eq for FftNormalization

impl StructuralPartialEq for FftNormalization