hanning.hpp

/*  function w = hanning(varargin)
%   HANNING   Hanning window.
%   HANNING(N) returns the N-point symmetric Hanning window in a column
%   vector.  Note that the first and last zero-weighted window samples
%   are not included.
%
%   HANNING(N,'symmetric') returns the same result as HANNING(N).
%
%   HANNING(N,'periodic') returns the N-point periodic Hanning window,
%   and includes the first zero-weighted window sample.
%
%   NOTE: Use the HANN function to get a Hanning window which has the
%          first and last zero-weighted samples.ep
    itype = 1 --> periodic
    itype = 0 --> symmetric
    default itype=0 (symmetric)

    Copyright 1988-2004 The MathWorks, Inc.
%   $Revision: 1.11.4.3 $  $Date: 2007/12/14 15:05:04 $
*/

#define PI 3.14159265359

float *rectwin(int N, short itype)
{
    float *w;
    w = (float*) calloc(N, sizeof(float));
    memset(w, 0, N*sizeof(float));

    for(int i = 0; i < N; i++)
    {
        w[i] = 1.0f;
    }

    return(w);
}

std::vector<float> bartlett(int N)
{
    std::vector<float> w(N, 0.0f);
    // w = (float*) calloc(N, sizeof(float));
    // memset(w, 0, N*sizeof(float));

    if (N == 1)
    {
        // Special case for n == 1.
        w[0] = 1.0;
    }
    else
    {
        const unsigned denominator = (N - 1);

        for (unsigned i = 0; i < N; ++i)
        {
            w[i] = 1.0 - fabs(2.0 * i - (N - 1)) / denominator;
        }
    }
    return(w);
}

std::vector<float> hanning(int N, short itype)
{
    int half, i, idx, n;
    std::vector<float> w(N, 0.0f);

    // w = (float*) calloc(N, sizeof(float));
    // memset(w, 0, N*sizeof(float));

    if(itype==1)    //periodic function
        n = N-1;
    else
        n = N;

    if(n%2==0)
    {
        half = n/2;
        for(i=0; i<half; i++) //CALC_HANNING   Calculates Hanning window samples.
            w[i] = 0.5 * (1 - cos(2*PI*(i+1) / (n+1)));

        idx = half-1;
        for(i=half; i<n; i++) {
            w[i] = w[idx];
            idx--;
        }
    }
    else
    {
        half = (n+1)/2;
        for(i=0; i<half; i++) //CALC_HANNING   Calculates Hanning window samples.
            w[i] = 0.5 * (1 - cos(2*PI*(i+1) / (n+1)));

        idx = half-2;
        for(i=half; i<n; i++) {
            w[i] = w[idx];
            idx--;
        }
    }

    if(itype==1)    //periodic function
    {
        for(i=N-1; i>=1; i--)
            w[i] = w[i-1];
        w[0] = 0.0;
    }
    return(w);
}