Examples with Complex imagingbook.lib.math.Complex used on opensource projects

Example 6 with Complex

use of imagingbook.lib.math.Complex in project imagingbook-common by imagingbook.

the class FourierDescriptorFromPolygon method makeDftSpectrumTrigonometric.

void makeDftSpectrumTrigonometric(int Mp) {
    // number of polygon vertices
    final int N = g.length;
    // number of Fourier coefficients
    final int M = 2 * Mp + 1;
    // dx[k] is the delta-x for polygon segment <k,k+1>
    double[] dx = new double[N];
    // dy[k] is the delta-y for polygon segment <k,k+1>
    double[] dy = new double[N];
    // lambda[k] is the length of the polygon segment <k,k+1>
    double[] lambda = new double[N];
    // T[k] is the cumulated path length at polygon vertex k in [0,K]
    double[] L = new double[N + 1];
    G = new Complex[M];
    L[0] = 0;
    for (int i = 0; i < N; i++) {
        // compute Dx, Dy, Dt and t tables
        dx[i] = g[(i + 1) % N].re - g[i].re;
        dy[i] = g[(i + 1) % N].im - g[i].im;
        lambda[i] = sqrt(sqr(dx[i]) + sqr(dy[i]));
        if (abs(lambda[i]) < EPSILON_DOUBLE) {
            throw new Error("Zero-length polygon segment!");
        }
        L[i + 1] = L[i] + lambda[i];
    }
    // Ln is the closed polygon length
    double Ln = L[N];
    // calculate DFT coefficient G[0]:
    // V[0].getX();
    double x0 = g[0].re;
    // V[0].getY();
    double y0 = g[0].im;
    double a0 = 0;
    double c0 = 0;
    for (int i = 0; i < N; i++) {
        // for each polygon vertex
        double s = (sqr(L[i + 1]) - sqr(L[i])) / (2 * lambda[i]) - L[i];
        // V[i].getX();
        double xi = g[i].re;
        // V[i].getY();
        double yi = g[i].im;
        a0 = a0 + s * dx[i] + (xi - x0) * lambda[i];
        c0 = c0 + s * dy[i] + (yi - y0) * lambda[i];
    }
    // G[0] = new Complex(x0 + a0/Ln, y0 + c0/Ln);
    this.setCoefficient(0, new Complex(x0 + a0 / Ln, y0 + c0 / Ln));
    // calculate remaining FD pairs G[-m], G[+m] for m = 1,...,Mp
    for (int m = 1; m <= Mp; m++) {
        // for each FD pair
        double w = 2 * PI * m / Ln;
        double a = 0, c = 0;
        double b = 0, d = 0;
        for (int i = 0; i < N; i++) {
            // for each polygon vertex
            double w0 = w * L[i];
            double w1 = w * L[(i + 1) % N];
            double dCos = cos(w1) - cos(w0);
            a = a + dCos * (dx[i] / lambda[i]);
            c = c + dCos * (dy[i] / lambda[i]);
            double dSin = sin(w1) - sin(w0);
            b = b + dSin * (dx[i] / lambda[i]);
            d = d + dSin * (dy[i] / lambda[i]);
        }
        double s = Ln / sqr(2 * PI * m);
        this.setCoefficient(+m, new Complex(s * (a + d), s * (c - b)));
        this.setCoefficient(-m, new Complex(s * (a - d), s * (b + c)));
    }
}

Example 7 with Complex

use of imagingbook.lib.math.Complex in project imagingbook-common by imagingbook.

the class FourierDescriptorUniform method DFT.

// -------------------------------------------------------------------
/**
 * DFT with the resulting spectrum (signal, if inverse) of the same length
 * as the input vector g. Not using sin/cos tables.
 *
 * @param g signal vector
 * @return DFT spectrum
 */
private Complex[] DFT(Complex[] g) {
    int M = g.length;
    // double[] cosTable = makeCosTable(M);	// cosTable[m] == cos(2*pi*m/M)
    // double[] sinTable = makeSinTable(M);
    Complex[] G = new Complex[M];
    // common scale factor (fwd/inverse differ!)
    double s = 1.0 / M;
    for (int m = 0; m < M; m++) {
        double Am = 0;
        double Bm = 0;
        for (int k = 0; k < M; k++) {
            double x = g[k].re;
            double y = g[k].im;
            double phi = 2 * Math.PI * m * k / M;
            double cosPhi = Math.cos(phi);
            double sinPhi = Math.sin(phi);
            Am = Am + x * cosPhi + y * sinPhi;
            Bm = Bm - x * sinPhi + y * cosPhi;
        }
        G[m] = new Complex(s * Am, s * Bm);
    }
    return G;
}

Example 8 with Complex

use of imagingbook.lib.math.Complex in project imagingbook-common by imagingbook.

the class Dft2d method doDft2d.

// ------------------------------------------------
public void doDft2d() {
    // in-place 2D Dft
    // do the rows:
    Complex[] row = makeComplexVector(width);
    Dft1d dftR = new Dft1d(width);
    for (int v = 0; v < height; v++) {
        getRow(v, row);
        Complex[] rowDft = dftR.DFT(row, forward);
        putRow(v, rowDft);
    }
    // do the columns:
    Complex[] col = makeComplexVector(height);
    Dft1d dftC = new Dft1d(height);
    for (int u = 0; u < width; u++) {
        getCol(u, col);
        Complex[] colDft = dftC.DFT(col, forward);
        putCol(u, colDft);
    }
}

Example 9 with Complex

use of imagingbook.lib.math.Complex in project imagingbook-common by imagingbook.

the class FourierDescriptor method setCoefficient.

public void setCoefficient(int m, Complex z) {
    int mm = Arithmetic.mod(m, G.length);
    G[mm] = new Complex(z);
}

Example 10 with Complex

use of imagingbook.lib.math.Complex in project imagingbook-common by imagingbook.

the class FourierDescriptor method distanceComplex.

public double distanceComplex(FourierDescriptor fd2, int Mp) {
    FourierDescriptor fd1 = this;
    Mp = Math.min(Mp, G.length / 2);
    double sum = 0;
    for (int m = -Mp; m <= Mp; m++) {
        if (m != 0) {
            Complex G1m = fd1.getCoefficient(m);
            Complex G2m = fd2.getCoefficient(m);
            double dRe = G1m.re - G2m.re;
            double dIm = G1m.im - G2m.im;
            sum = sum + dRe * dRe + dIm * dIm;
        }
    }
    return Math.sqrt(sum);
}