_singleTransform2(data, out, outOff, off, step) {
        // radix-2 implementation
        // NOTE: Only called for len=4

        const evenR = data[off];
        const evenI = data[off + 1];
        const oddR = data[off + step];
        const oddI = data[off + step + 1];

        out[outOff] = evenR + oddR;
        out[outOff + 1] = evenI + oddI;
        out[outOff + 2] = evenR - oddR;
        out[outOff + 3] = evenI - oddI;
    }
Performs a radix-2 implementation of a discrete Fourier transform on a given set of data.

@param {Float64Array} data The input buffer of data to be transformed.
@param {Float64Array} out The output buffer for the transformed data.
@param {number} outOff The offset at which to write the output data.
@param {number} off The offset at which to begin reading the input data.
@param {number} step The step size for indexing the input data.
@returns {void}