Astra1DMagnetoStatic.cpp

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#include "Fields/Astra1DMagnetoStatic.h"
#include "Fields/Fieldmap.hpp"
#include "Physics/Physics.h"
#include "Utilities/GeneralClassicException.h"
#include "Utilities/Util.h"
 
#include "gsl/gsl_interp.h"
#include "gsl/gsl_spline.h"
#include "gsl/gsl_fft_real.h"
 
#include <fstream>
#include <ios>
 
 
Astra1DMagnetoStatic::Astra1DMagnetoStatic(std::string aFilename)
    : Fieldmap(aFilename),
      FourCoefs_m(nullptr) {
    std::ifstream file;
    int skippedValues = 0;
    std::string tmpString;
    double tmpDouble;
 
    Type = TAstraMagnetoStatic;
 
    // open field map, parse it and disable element on error
    file.open(Filename_m.c_str());
    if (file.good()) {
        bool parsing_passed = true;
        try {
            parsing_passed = interpretLine<std::string, int>(file, tmpString, accuracy_m);
        } catch (GeneralClassicException &e) {
            parsing_passed = interpretLine<std::string, int, std::string>(file, tmpString, accuracy_m, tmpString);
 
            tmpString = Util::toUpper(tmpString);
            if (tmpString != "TRUE" &&
                tmpString != "FALSE")
                throw GeneralClassicException("Astra1DMagnetoStatic::Astra1DMagnetoStatic",
                                              "The third string on the first line of 1D field "
                                              "maps has to be either TRUE or FALSE");
 
            normalize_m = (tmpString == "TRUE");
        }
        parsing_passed = parsing_passed &&
                         interpretLine<double, double>(file, zbegin_m, tmpDouble);
 
        double tmpDouble2 = zbegin_m;
        while(!file.eof() && parsing_passed) {
            parsing_passed = interpretLine<double, double>(file, zend_m, tmpDouble, false);
            if (zend_m - tmpDouble2 > 1e-10) {
                tmpDouble2 = zend_m;
            } else if (parsing_passed) {
                ++ skippedValues;
            }
        }
 
        file.close();
        num_gridpz_m = lines_read_m - 2 - skippedValues;
        lines_read_m = 0;
 
        if (!parsing_passed && !file.eof()) {
            disableFieldmapWarning();
            zend_m = zbegin_m - 1e-3;
            throw GeneralClassicException("Astra1DMagnetoStatic::Astra1DMagnetoStatic",
                                          "An error occured when reading the fieldmap '" + Filename_m + "'");
        }
        length_m = 2.0 * num_gridpz_m * (zend_m - zbegin_m) / (num_gridpz_m - 1);
    } else {
        noFieldmapWarning();
        zbegin_m = 0.0;
        zend_m = -1e-3;
    }
}
 
Astra1DMagnetoStatic::~Astra1DMagnetoStatic() {
    freeMap();
}
 
void Astra1DMagnetoStatic::readMap() {
    if (FourCoefs_m == nullptr) {
        // declare variables and allocate memory
        std::ifstream in;
 
        bool parsing_passed = true;
 
        std::string tmpString;
 
        double Bz_max = 0.0;
        double dz = (zend_m - zbegin_m) / (num_gridpz_m - 1);
        double tmpDouble = zbegin_m - dz;
 
        double *RealValues = new double[2 * num_gridpz_m];
        double *zvals = new double[num_gridpz_m];
 
        gsl_spline *Bz_interpolant = gsl_spline_alloc(gsl_interp_cspline, num_gridpz_m);
        gsl_interp_accel *Bz_accel = gsl_interp_accel_alloc();
 
        gsl_fft_real_wavetable *real = gsl_fft_real_wavetable_alloc(2 * num_gridpz_m);
        gsl_fft_real_workspace *work = gsl_fft_real_workspace_alloc(2 * num_gridpz_m);
 
        FourCoefs_m = new double[2 * accuracy_m - 1];
 
        // read in and parse field map
        in.open(Filename_m.c_str());
        getLine(in, tmpString);
 
        for (int i = 0; i < num_gridpz_m && parsing_passed;/* skip increment on i here */) {
            parsing_passed = interpretLine<double, double>(in, zvals[i], RealValues[i]);
            // the sequence of z-position should be strictly increasing
            // drop sampling points that don't comply to this
            if (zvals[i] - tmpDouble > 1e-10) {
                if (std::abs(RealValues[i]) > Bz_max) {
                    Bz_max = std::abs(RealValues[i]);
                }
                tmpDouble = zvals[i];
                ++ i; // increment i only if sampling point is accepted
            }
        }
        in.close();
 
        gsl_spline_init(Bz_interpolant, zvals, RealValues, num_gridpz_m);
 
        // get equidistant sampling from the, possibly, non-equidistant sampling
        // using cubic spline for this
        int ii = num_gridpz_m;
        for (int i = 0; i < num_gridpz_m - 1; ++ i, ++ ii) {
            double z = zbegin_m + dz * i;
            RealValues[ii] = gsl_spline_eval(Bz_interpolant, z, Bz_accel);
        }
        RealValues[ii ++] = RealValues[num_gridpz_m - 1];
        // prepend mirror sampling points such that field values are periodic for sure
        -- ii; // ii == 2*num_gridpz_m at the moment
        for (int i = 0; i < num_gridpz_m; ++ i, -- ii) {
            RealValues[i] = RealValues[ii];
        }
 
        gsl_fft_real_transform(RealValues, 1, 2 * num_gridpz_m, real, work);
 
        if (!normalize_m) {
            Bz_max = 1.0;
        }
        // normalize to Bz_max = 1 A/m
        FourCoefs_m[0] = RealValues[0] / (Bz_max * 2. * num_gridpz_m);
        for (int i = 1; i < 2 * accuracy_m - 1; i++) {
            FourCoefs_m[i] = RealValues[i] / (Bz_max * num_gridpz_m);
        }
 
        gsl_spline_free(Bz_interpolant);
        gsl_interp_accel_free(Bz_accel);
 
        gsl_fft_real_workspace_free(work);
        gsl_fft_real_wavetable_free(real);
 
        delete[] zvals;
        delete[] RealValues;
 
        INFOMSG(level3 << typeset_msg("read in fieldmap '" + Filename_m  + "'", "info") << endl);
    }
}
 
void Astra1DMagnetoStatic::freeMap() {
    if (FourCoefs_m != nullptr) {
 
        delete[] FourCoefs_m;
        FourCoefs_m = nullptr;
 
        INFOMSG(level3 << typeset_msg("freed fieldmap '" + Filename_m  + "'", "info") << endl);
    }
}
 
bool Astra1DMagnetoStatic::getFieldstrength(const Vector_t &R, Vector_t &/*E*/, Vector_t &B) const {
    // do fourier interpolation in z-direction
    const double RR2 = R(0) * R(0) + R(1) * R(1);
 
    const double kz = Physics::two_pi * (R(2) - zbegin_m) / length_m + Physics::pi;
 
    double ez = FourCoefs_m[0];
    double ezp = 0.0;
    double ezpp = 0.0;
    double ezppp = 0.0;
 
    int n = 1;
    for (int l = 1; l < accuracy_m ; l++, n += 2) {
        double somefactor_base =  Physics::two_pi / length_m * l;    // = \frac{d(kz*l)}{dz}
        double somefactor = 1.0;
        double coskzl = cos(kz * l);
        double sinkzl = sin(kz * l);
        ez    += (FourCoefs_m[n] * coskzl - FourCoefs_m[n + 1] * sinkzl);
        somefactor *= somefactor_base;
        ezp   += somefactor * (-FourCoefs_m[n] * sinkzl - FourCoefs_m[n + 1] * coskzl);
        somefactor *= somefactor_base;
        ezpp  += somefactor * (-FourCoefs_m[n] * coskzl + FourCoefs_m[n + 1] * sinkzl);
        somefactor *= somefactor_base;
        ezppp += somefactor * (FourCoefs_m[n] * sinkzl + FourCoefs_m[n + 1] * coskzl);
    }
    // expand the field off-axis
    const double BfieldR = -ezp / 2. + ezppp / 16. * RR2;
 
    B(0) += BfieldR * R(0);
    B(1) += BfieldR * R(1);
    B(2) += ez - ezpp * RR2 / 4.;
 
    return false;
}
 
bool Astra1DMagnetoStatic::getFieldDerivative(const Vector_t &/*R*/, Vector_t &/*E*/, Vector_t &/*B*/, const DiffDirection &/*dir*/) const {
    return false;
}
 
void Astra1DMagnetoStatic::getFieldDimensions(double &zBegin, double &zEnd) const {
    zBegin = zbegin_m;
    zEnd = zend_m;
}
void Astra1DMagnetoStatic::getFieldDimensions(double &/*xIni*/, double &/*xFinal*/, double &/*yIni*/, double &/*yFinal*/, double &/*zIni*/, double &/*zFinal*/) const {}
 
void Astra1DMagnetoStatic::swap()
{ }
 
void Astra1DMagnetoStatic::getInfo(Inform *msg) {
    (*msg) << Filename_m << " (1D magnetostatic); zini= " << zbegin_m << " m; zfinal= " << zend_m << " m;" << endl;
}
 
double Astra1DMagnetoStatic::getFrequency() const {
    return 0.0;
}
 
void Astra1DMagnetoStatic::setFrequency(double /*freq*/)
{ }