import { Seismogram, SeismogramDisplayData } from "./seismogram.mjs";
import { Complex } from "./oregondsputil.mjs";
/**
 * A higher level function to calculate DFT. Returns a
 * FFTResult for easier access to the result as
 * complex, amp, phase arrays. Calls calcDFT internally.
 * Inverse FFT is available as FFTResult.fftInverse().
 *
 * @param seis seismogram or SeismogramDisplayData to transform
 * @returns fft of seismogram
 */
export declare function fftForward(seis: Seismogram | SeismogramDisplayData): FFTResult;
/**
 * Calculates the discrete fourier transform using the OregonDSP library.
 *
 * This is a lower level function, fftForward is better for most uses.
 *
 * @param   timeseries timeseries array
 * @returns           DFT as packed array Float32Array
 */
export declare function calcDFT(timeseries: Int32Array | Float32Array | Float64Array): Float32Array;
/**
 * Calculates the inverse discrete fourier transform using the oregondsp library.
 *
 * @param   packedFreq DFT as packed array Float32Array
 * @param   numPoints     number of points in original timeseries array.
 * @returns           inverse of DFT as a timeseries array
 */
export declare function inverseDFT(packedFreq: Float32Array<ArrayBufferLike>, numPoints: number): Float32Array;
/**
 * Finds smallest power of two >= input number.
 *
 * @param  fftlength               input number
 * @returns           tuple of N and log2N, like [16,4]
 */
export declare function findPowerTwo(fftlength: number): [number, number];
/**
 * Results of FFT calculation. Allows convertion of the packed real/imag array output from calcDFT into
 * amplitude and phase.
 */
export declare class FFTResult {
    /** number of points in the original timeseries, may be less than fft size. */
    origLength: number;
    packedFreq: Float32Array;
    /** number of points in the fft, usually power of 2 larger than origLength. */
    numPoints: number;
    /** sample rate of the original time series, maybe be null. */
    sampleRate: number;
    /** optional units of the original data for display purposes. */
    inputUnits: string | undefined;
    /**
     * optional reference to SeismogramDisplayData when calculated from a seismogram.
     *  Useful for creating title, etc.
     */
    seismogramDisplayData: SeismogramDisplayData | undefined;
    constructor(origLength: number, sampleRate: number);
    /**
     * Factory method to create FFTResult from packed array.
     *
     * @param   packedFreq real and imag values in packed format
     * @param   origLength length of the original timeseries before padding.
     * @param   sampleRate sample rate of original data
     * @returns            FFTResult
     */
    static createFromPackedFreq(packedFreq: Float32Array, origLength: number, sampleRate: number): FFTResult;
    /**
     * Factory method to create from array of complex numbers.
     *
     * @param   complexArray real and imag values as array of Complex objects.
     * @param   origLength   length of the original timeseries before padding.
     * @param   sampleRate sample rate of original data
     * @returns               FFTResult
     */
    static createFromComplex(complexArray: Array<InstanceType<typeof Complex>>, origLength: number, sampleRate: number): FFTResult;
    /**
     * Factory method to create from amp and phase arrays
     *
     * @param   amp        amplitude values
     * @param   phase      phase values
     * @param   origLength length of the original timeseries before padding.
     * @param   sampleRate sample rate of original data
     * @returns             FFTResult
     */
    static createFromAmpPhase(amp: Float32Array, phase: Float32Array, origLength: number, sampleRate: number): FFTResult;
    /**
     * The minimum non-zero frequency in the fft
     *
     * @returns fundamental frequency
     */
    get fundamentalFrequency(): number;
    asComplex(): Array<InstanceType<typeof Complex>>;
    asAmpPhase(): [Float32Array, Float32Array];
    /**
     * calculates the inverse fft of this.packedFreq
     *
     * @returns time domain representation
     */
    fftInverse(): Float32Array;
    frequencies(): Float32Array;
    get numFrequencies(): number;
    get minFrequency(): number;
    get maxFrequency(): number;
    amplitudes(): Float32Array;
    phases(): Float32Array;
    clone(): FFTResult;
}
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