fftsg.c

2维fft程序

            k1 += nh;
            a[j1 - 1] = -a[j1 - 1];
            xr = a[j1];
            xi = -a[j1 + 1];
            yr = a[k1];
            yi = -a[k1 + 1];
            a[j1] = yr;
            a[j1 + 1] = yi;
            a[k1] = xr;
            a[k1 + 1] = xi;
            a[k1 + 3] = -a[k1 + 3];
            j1 += nm;
            k1 += 2 * nm;
            xr = a[j1];
            xi = -a[j1 + 1];
            yr = a[k1];
            yi = -a[k1 + 1];
            a[j1] = yr;
            a[j1 + 1] = yi;
            a[k1] = xr;
            a[k1 + 1] = xi;
            j1 += nm;
            k1 -= nm;
            xr = a[j1];
            xi = -a[j1 + 1];
            yr = a[k1];
            yi = -a[k1 + 1];
            a[j1] = yr;
            a[j1 + 1] = yi;
            a[k1] = xr;
            a[k1 + 1] = xi;
            j1 -= 2;
            k1 -= nh;
            xr = a[j1];
            xi = -a[j1 + 1];
            yr = a[k1];
            yi = -a[k1 + 1];
            a[j1] = yr;
            a[j1 + 1] = yi;
            a[k1] = xr;
            a[k1 + 1] = xi;
            j1 += nh + 2;
            k1 += nh + 2;
            xr = a[j1];
            xi = -a[j1 + 1];
            yr = a[k1];
            yi = -a[k1 + 1];
            a[j1] = yr;
            a[j1 + 1] = yi;
            a[k1] = xr;
            a[k1 + 1] = xi;
            j1 -= nh - nm;
            k1 += 2 * nm - 2;
            a[j1 - 1] = -a[j1 - 1];
            xr = a[j1];
            xi = -a[j1 + 1];
            yr = a[k1];
            yi = -a[k1 + 1];
            a[j1] = yr;
            a[j1 + 1] = yi;
            a[k1] = xr;
            a[k1 + 1] = xi;
            a[k1 + 3] = -a[k1 + 3];
        }
    } else {
        for (k = 0; k < m; k++) {
            for (j = 0; j < k; j++) {
                j1 = 4 * j + ip[m + k];
                k1 = 4 * k + ip[m + j];
                xr = a[j1];
                xi = -a[j1 + 1];
                yr = a[k1];
                yi = -a[k1 + 1];
                a[j1] = yr;
                a[j1 + 1] = yi;
                a[k1] = xr;
                a[k1 + 1] = xi;
                j1 += nm;
                k1 += nm;
                xr = a[j1];
                xi = -a[j1 + 1];
                yr = a[k1];
                yi = -a[k1 + 1];
                a[j1] = yr;
                a[j1 + 1] = yi;
                a[k1] = xr;
                a[k1 + 1] = xi;
                j1 += nh;
                k1 += 2;
                xr = a[j1];
                xi = -a[j1 + 1];
                yr = a[k1];
                yi = -a[k1 + 1];
                a[j1] = yr;
                a[j1 + 1] = yi;
                a[k1] = xr;
                a[k1 + 1] = xi;
                j1 -= nm;
                k1 -= nm;
                xr = a[j1];
                xi = -a[j1 + 1];
                yr = a[k1];
                yi = -a[k1 + 1];
                a[j1] = yr;
                a[j1 + 1] = yi;
                a[k1] = xr;
                a[k1 + 1] = xi;
                j1 += 2;
                k1 += nh;
                xr = a[j1];
                xi = -a[j1 + 1];
                yr = a[k1];
                yi = -a[k1 + 1];
                a[j1] = yr;
                a[j1 + 1] = yi;
                a[k1] = xr;
                a[k1 + 1] = xi;
                j1 += nm;
                k1 += nm;
                xr = a[j1];
                xi = -a[j1 + 1];
                yr = a[k1];
                yi = -a[k1 + 1];
                a[j1] = yr;
                a[j1 + 1] = yi;
                a[k1] = xr;
                a[k1 + 1] = xi;
                j1 -= nh;
                k1 -= 2;
                xr = a[j1];
                xi = -a[j1 + 1];
                yr = a[k1];
                yi = -a[k1 + 1];
                a[j1] = yr;
                a[j1 + 1] = yi;
                a[k1] = xr;
                a[k1 + 1] = xi;
                j1 -= nm;
                k1 -= nm;
                xr = a[j1];
                xi = -a[j1 + 1];
                yr = a[k1];
                yi = -a[k1 + 1];
                a[j1] = yr;
                a[j1 + 1] = yi;
                a[k1] = xr;
                a[k1 + 1] = xi;
            }
            k1 = 4 * k + ip[m + k];
            j1 = k1 + 2;
            k1 += nh;
            a[j1 - 1] = -a[j1 - 1];
            xr = a[j1];
            xi = -a[j1 + 1];
            yr = a[k1];
            yi = -a[k1 + 1];
            a[j1] = yr;
            a[j1 + 1] = yi;
            a[k1] = xr;
            a[k1 + 1] = xi;
            a[k1 + 3] = -a[k1 + 3];
            j1 += nm;
            k1 += nm;
            a[j1 - 1] = -a[j1 - 1];
            xr = a[j1];
            xi = -a[j1 + 1];
            yr = a[k1];
            yi = -a[k1 + 1];
            a[j1] = yr;
            a[j1 + 1] = yi;
            a[k1] = xr;
            a[k1 + 1] = xi;
            a[k1 + 3] = -a[k1 + 3];
        }
    }
}


void bitrv216(double *a)
{
    double x1r, x1i, x2r, x2i, x3r, x3i, x4r, x4i, 
        x5r, x5i, x7r, x7i, x8r, x8i, x10r, x10i, 
        x11r, x11i, x12r, x12i, x13r, x13i, x14r, x14i;
    
    x1r = a[2];
    x1i = a[3];
    x2r = a[4];
    x2i = a[5];
    x3r = a[6];
    x3i = a[7];
    x4r = a[8];
    x4i = a[9];
    x5r = a[10];
    x5i = a[11];
    x7r = a[14];
    x7i = a[15];
    x8r = a[16];
    x8i = a[17];
    x10r = a[20];
    x10i = a[21];
    x11r = a[22];
    x11i = a[23];
    x12r = a[24];
    x12i = a[25];
    x13r = a[26];
    x13i = a[27];
    x14r = a[28];
    x14i = a[29];
    a[2] = x8r;
    a[3] = x8i;
    a[4] = x4r;
    a[5] = x4i;
    a[6] = x12r;
    a[7] = x12i;
    a[8] = x2r;
    a[9] = x2i;
    a[10] = x10r;
    a[11] = x10i;
    a[14] = x14r;
    a[15] = x14i;
    a[16] = x1r;
    a[17] = x1i;
    a[20] = x5r;
    a[21] = x5i;
    a[22] = x13r;
    a[23] = x13i;
    a[24] = x3r;
    a[25] = x3i;
    a[26] = x11r;
    a[27] = x11i;
    a[28] = x7r;
    a[29] = x7i;
}


void bitrv216neg(double *a)
{
    double x1r, x1i, x2r, x2i, x3r, x3i, x4r, x4i, 
        x5r, x5i, x6r, x6i, x7r, x7i, x8r, x8i, 
        x9r, x9i, x10r, x10i, x11r, x11i, x12r, x12i, 
        x13r, x13i, x14r, x14i, x15r, x15i;
    
    x1r = a[2];
    x1i = a[3];
    x2r = a[4];
    x2i = a[5];
    x3r = a[6];
    x3i = a[7];
    x4r = a[8];
    x4i = a[9];
    x5r = a[10];
    x5i = a[11];
    x6r = a[12];
    x6i = a[13];
    x7r = a[14];
    x7i = a[15];
    x8r = a[16];
    x8i = a[17];
    x9r = a[18];
    x9i = a[19];
    x10r = a[20];
    x10i = a[21];
    x11r = a[22];
    x11i = a[23];
    x12r = a[24];
    x12i = a[25];
    x13r = a[26];
    x13i = a[27];
    x14r = a[28];
    x14i = a[29];
    x15r = a[30];
    x15i = a[31];
    a[2] = x15r;
    a[3] = x15i;
    a[4] = x7r;
    a[5] = x7i;
    a[6] = x11r;
    a[7] = x11i;
    a[8] = x3r;
    a[9] = x3i;
    a[10] = x13r;
    a[11] = x13i;
    a[12] = x5r;
    a[13] = x5i;
    a[14] = x9r;
    a[15] = x9i;
    a[16] = x1r;
    a[17] = x1i;
    a[18] = x14r;
    a[19] = x14i;
    a[20] = x6r;
    a[21] = x6i;
    a[22] = x10r;
    a[23] = x10i;
    a[24] = x2r;
    a[25] = x2i;
    a[26] = x12r;
    a[27] = x12i;
    a[28] = x4r;
    a[29] = x4i;
    a[30] = x8r;
    a[31] = x8i;
}


void bitrv208(double *a)
{
    double x1r, x1i, x3r, x3i, x4r, x4i, x6r, x6i;
    
    x1r = a[2];
    x1i = a[3];
    x3r = a[6];
    x3i = a[7];
    x4r = a[8];
    x4i = a[9];
    x6r = a[12];
    x6i = a[13];
    a[2] = x4r;
    a[3] = x4i;
    a[6] = x6r;
    a[7] = x6i;
    a[8] = x1r;
    a[9] = x1i;
    a[12] = x3r;
    a[13] = x3i;
}


void bitrv208neg(double *a)
{
    double x1r, x1i, x2r, x2i, x3r, x3i, x4r, x4i, 
        x5r, x5i, x6r, x6i, x7r, x7i;
    
    x1r = a[2];
    x1i = a[3];
    x2r = a[4];
    x2i = a[5];
    x3r = a[6];
    x3i = a[7];
    x4r = a[8];
    x4i = a[9];
    x5r = a[10];
    x5i = a[11];
    x6r = a[12];
    x6i = a[13];
    x7r = a[14];
    x7i = a[15];
    a[2] = x7r;
    a[3] = x7i;
    a[4] = x3r;
    a[5] = x3i;
    a[6] = x5r;
    a[7] = x5i;
    a[8] = x1r;
    a[9] = x1i;
    a[10] = x6r;
    a[11] = x6i;
    a[12] = x2r;
    a[13] = x2i;
    a[14] = x4r;
    a[15] = x4i;
}


void cftf1st(int n, double *a, double *w)
{
    int j, j0, j1, j2, j3, k, m, mh;
    double wn4r, csc1, csc3, wk1r, wk1i, wk3r, wk3i, 
        wd1r, wd1i, wd3r, wd3i;
    double x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i, 
        y0r, y0i, y1r, y1i, y2r, y2i, y3r, y3i;
    
    mh = n >> 3;
    m = 2 * mh;
    j1 = m;
    j2 = j1 + m;
    j3 = j2 + m;
    x0r = a[0] + a[j2];
    x0i = a[1] + a[j2 + 1];
    x1r = a[0] - a[j2];
    x1i = a[1] - a[j2 + 1];
    x2r = a[j1] + a[j3];
    x2i = a[j1 + 1] + a[j3 + 1];
    x3r = a[j1] - a[j3];
    x3i = a[j1 + 1] - a[j3 + 1];
    a[0] = x0r + x2r;
    a[1] = x0i + x2i;
    a[j1] = x0r - x2r;
    a[j1 + 1] = x0i - x2i;
    a[j2] = x1r - x3i;
    a[j2 + 1] = x1i + x3r;
    a[j3] = x1r + x3i;
    a[j3 + 1] = x1i - x3r;
    wn4r = w[1];
    csc1 = w[2];
    csc3 = w[3];
    wd1r = 1;
    wd1i = 0;
    wd3r = 1;
    wd3i = 0;
    k = 0;
    for (j = 2; j < mh - 2; j += 4) {
        k += 4;
        wk1r = csc1 * (wd1r + w[k]);
        wk1i = csc1 * (wd1i + w[k + 1]);
        wk3r = csc3 * (wd3r + w[k + 2]);
        wk3i = csc3 * (wd3i + w[k + 3]);
        wd1r = w[k];
        wd1i = w[k + 1];
        wd3r = w[k + 2];
        wd3i = w[k + 3];
        j1 = j + m;
        j2 = j1 + m;
        j3 = j2 + m;
        x0r = a[j] + a[j2];
        x0i = a[j + 1] + a[j2 + 1];
        x1r = a[j] - a[j2];
        x1i = a[j + 1] - a[j2 + 1];
        y0r = a[j + 2] + a[j2 + 2];
        y0i = a[j + 3] + a[j2 + 3];
        y1r = a[j + 2] - a[j2 + 2];
        y1i = a[j + 3] - a[j2 + 3];
        x2r = a[j1] + a[j3];
        x2i = a[j1 + 1] + a[j3 + 1];
        x3r = a[j1] - a[j3];
        x3i = a[j1 + 1] - a[j3 + 1];
        y2r = a[j1 + 2] + a[j3 + 2];
        y2i = a[j1 + 3] + a[j3 + 3];
        y3r = a[j1 + 2] - a[j3 + 2];
        y3i = a[j1 + 3] - a[j3 + 3];
        a[j] = x0r + x2r;
        a[j + 1] = x0i + x2i;
        a[j + 2] = y0r + y2r;
        a[j + 3] = y0i + y2i;
        a[j1] = x0r - x2r;
        a[j1 + 1] = x0i - x2i;
        a[j1 + 2] = y0r - y2r;
        a[j1 + 3] = y0i - y2i;
        x0r = x1r - x3i;
        x0i = x1i + x3r;
        a[j2] = wk1r * x0r - wk1i * x0i;
        a[j2 + 1] = wk1r * x0i + wk1i * x0r;
        x0r = y1r - y3i;
        x0i = y1i + y3r;
        a[j2 + 2] = wd1r * x0r - wd1i * x0i;
        a[j2 + 3] = wd1r * x0i + wd1i * x0r;
        x0r = x1r + x3i;
        x0i = x1i - x3r;
        a[j3] = wk3r * x0r + wk3i * x0i;
        a[j3 + 1] = wk3r * x0i - wk3i * x0r;
        x0r = y1r + y3i;
        x0i = y1i - y3r;
        a[j3 + 2] = wd3r * x0r + wd3i * x0i;
        a[j3 + 3] = wd3r * x0i - wd3i * x0r;
        j0 = m - j;
        j1 = j0 + m;
        j2 = j1 + m;
        j3 = j2 + m;
        x0r = a[j0] + a[j2];
        x0i = a[j0 + 1] + a[j2 + 1];
        x1r = a[j0] - a[j2];
        x1i = a[j0 + 1] - a[j2 + 1];
        y0r = a[j0 - 2] + a[j2 - 2];
        y0i = a[j0 - 1] + a[j2 - 1];
        y1r = a[j0 - 2] - a[j2 - 2];
        y1i = a[j0 - 1] - a[j2 - 1];
        x2r = a[j1] + a[j3];
        x2i = a[j1 + 1] + a[j3 + 1];
        x3r = a[j1] - a[j3];
        x3i = a[j1 + 1] - a[j3 + 1];
        y2r = a[j1 - 2] + a[j3 - 2];
        y2i = a[j1 - 1] + a[j3 - 1];
        y3r = a[j1 - 2] - a[j3 - 2];