Function dct 

pub fn dct<T>(
    x: &[T],
    dcttype: Option<DCTType>,
    norm: Option<&str>,
) -> Result<Vec<f64>, FFTError>
where
    T: NumCast + Copy + Debug,

Compute the 1-dimensional discrete cosine transform.

Arguments

• x - Input array
• dct_type - Type of DCT to perform (default: Type2)
• norm - Normalization mode (None, “ortho”)

Returns

• The DCT of the input array

Examples

use scirs2_fft::{dct, DCTType};

// Generate a simple signal
let signal = vec![1.0, 2.0, 3.0, 4.0];

// Compute DCT-II of the signal
let dct_coeffs = dct(&signal, Some(DCTType::Type2), Some("ortho")).expect("Operation failed");

// The DC component (mean of the signal) is enhanced in DCT
let mean = 2.5;  // (1+2+3+4)/4
assert!((dct_coeffs[0] / 2.0 - mean).abs() < 1e-10);

Errors

Returns an error if the input values cannot be converted to f64, or if other computation errors occur (e.g., invalid array dimensions).