EquationSystemSolver Class Reference

#include <eq_system_solver.h>

Static Public Member Functions
template<typename T >
static void	solve (Matrix1D< T > &bXt, Matrix1D< T > &bYt, Matrix2D< T > &At, Matrix1D< T > &shiftXt, Matrix1D< T > &shiftYt, int verbosity, int iterations)

Detailed Description

Definition at line 34 of file eq_system_solver.h.

Member Function Documentation

solve()

template<typename T >

void EquationSystemSolver::solve ( Matrix1D< T > &  bXt, Matrix1D< T > &  bYt, Matrix2D< T > &  At, Matrix1D< T > &  shiftXt, Matrix1D< T > &  shiftYt, int  verbosity, int  iterations  )

static

Method computes absolute shifts from relative shifts

Parameters

bX	relative shifts in X dim
bY	relative shifts in Y dim
A	system matrix to be used
shiftX	absolute shifts in X dim
shiftY	absolute shifts in Y dim
verbosity	level
iterations	of the solver

Definition at line 36 of file eq_system_solver.cpp.

                                                             {
    Matrix1D<double> ex;
    Matrix1D<double> ey;
    WeightedLeastSquaresHelperMany helper;
    helper.bs.resize(2);
    std::vector<Matrix1D<double>> shifts(2);
    Matrix2D<double> A;
    Matrix1D<double> bX;
    Matrix1D<double> bY;
    Matrix1D<double> &shiftX = shifts[0];
    Matrix1D<double> &shiftY = shifts[1];
    
    typeCast(bXt, bX);
    typeCast(bYt, bY);
    typeCast(shiftXt, shiftX);
    typeCast(shiftYt, shiftY);

    helper.w.resizeNoCopy(VEC_XSIZE(bX));
    helper.w.initConstant(1);

    int it = 0;
    double mean;
    double varbX;
    double varbY;
    bX.computeMeanAndStddev(mean, varbX);
    varbX *= varbX;
    bY.computeMeanAndStddev(mean, varbY);
    varbY *= varbY;
    if (verbosity > 1)
        std::cout << "Solving equation system ...\n";
    do {
        // Solve the equation system
        helper.bs[0] = bX;
        helper.bs[1] = bY;
        typeCast(At, helper.A);
        weightedLeastSquares(helper, shifts); // we have updated A, is that OK?
        
        // Compute residuals
        ex = bX - helper.A * shiftX;
        ey = bY - helper.A * shiftY;

        // Compute R2
        double stddeveX;
        ex.computeMeanAndStddev(mean, stddeveX);
        double stddeveY;
        ey.computeMeanAndStddev(mean, stddeveY);
        double R2x = 1 - (stddeveX * stddeveX) / varbX;
        double R2y = 1 - (stddeveY * stddeveY) / varbY;
        if (verbosity > 1)
            std::cout << "Iteration " << it << " R2x=" << R2x << " R2y=" << R2y
                    << std::endl;

        // Identify outliers
        double oldWeightSum = helper.w.sum();
        FOR_ALL_ELEMENTS_IN_MATRIX1D (ex) {
            if (fabs(VEC_ELEM(ex, i)) > 3 * stddeveX
                    || fabs(VEC_ELEM(ey, i)) > 3 * stddeveY)
                VEC_ELEM(helper.w, i) = 0.0;
        }
        double newWeightSum = helper.w.sum();
        if ((newWeightSum == oldWeightSum) && (verbosity > 1)){
            std::cout << "No outlier found\n\n";
            break;
        } else if (verbosity > 1)
            std::cout << "Found " << (int) (oldWeightSum - newWeightSum)
                    << " outliers\n\n";

        it++;
    } while (it < iterations);

    typeCast(shiftX, shiftXt);
    typeCast(shiftY, shiftYt);
}

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The documentation for this class was generated from the following files:

• xmipp/libraries/reconstruction/eq_system_solver.h
• xmipp/libraries/reconstruction/eq_system_solver.cpp