TimeDomainRCS/main.cc

#include <omp.h>             // For OpenMP parallelization
#include <mutex>             // For thread-safe access
#include <sstream>           // For building file names
#include <iomanip>           // For zero-padded formatting
#include <filesystem>        // For file existence check
#include <iostream>          // For console output
#include <vector>            // For dynamic arrays
#include <array>             // For fixed-size field vectors
#include <string>            // For file and path strings
#include <cstring>           // required for strncpy

#include "vtr.h"             // real vector
#include "cvtr.h"            // complex vector
#include "Constants.h"

#include <sys/wait.h>
#include <sys/times.h>

#include "rapidcsv.h"        // For easy CSV reading
#include "OutputSurfMesh.h"  // For tri file operations

#include <complex>        // For complex numbers


#include <fstream>           // For file operations
#include <cstdlib>           // For std::exit
#include <algorithm>        // For std::copy
#include <tuple>             // For std::tuple


#include <fftw3.h>           // FFT header file



namespace fs = std::filesystem;

// Define types for 3D field vectors and time series containers
using FieldSeries3D = std::vector<std::vector<vtr>>;     // [probe][time][field polarization]
using FFTSeries3D   = std::vector<std::vector<cVtr>>;    // [probe][freq][field polarization]
using current3D     = std::vector<std::vector<std::vector<cVtr>>>; // [freq][traingle][nodes]
using current2D     = std::vector<std::vector<cVtr>>; // [triangle][nodes]

// Count number of probe files in the folder
int countCSVFiles(const std::string& folder)
{
    int count = 0;
    for (const auto& entry : fs::directory_iterator(folder))
    {
        if (!entry.is_regular_file())
            continue;

        if (entry.path().extension() == ".csv")
            ++count;
    }
    return count;
}

// Function to load electric and magnetic field data from CSV files over time
void loadSeparatedProbeFields(
    const std::string& folder,            // Directory containing CSV files
    const std::string& baseName,          // Base file name (e.g., "Probes_sphere")
    int startTimeStep,                    // Index of the first time step (e.g., 0)
    int timeStepIncrement,                // Step size between time steps (e.g., 1)
    int nFiles,                           // Number of time steps to read (inclusive)
    std::vector<std::vector<vtr>>& E_fieldSeries, // Output: E-field [probe][time]
    std::vector<std::vector<vtr>>& H_fieldSeries  // Output: H-field [probe][time]
)
{
    std::mutex mtx;
    int numProbes = 0;
    bool initialized = false;



    #pragma omp parallel for
    for (int t = 0; t < nFiles; ++t)
    {
        int Time = startTimeStep + t * timeStepIncrement;

        std::stringstream filename;
        if (Time < 10000)
            filename << folder << "/" << baseName << "_"
                     << std::setfill('0') << std::setw(4) << Time << ".csv";
        else
            filename << folder << "/" << baseName << "_" << Time << ".csv";

        if (!fs::exists(filename.str()))
        {
            #pragma omp critical
            std::cerr << "[Warning] File not found: " << filename.str() << std::endl;
            continue;
        }

        rapidcsv::Document doc(filename.str(), rapidcsv::LabelParams(0, -1));
        int numRows = doc.GetRowCount();

        for (int i = 0; i < numRows; ++i)
        {
            std::vector<float> row = doc.GetRow<float>(i);

            if (row.size() < 6)
            {
                #pragma omp critical
                std::cerr << "[Error] Row " << i << " in " << filename.str()
                          << " has fewer than 6 columns.\n";
                continue;
            }

            vtr E(row[0], row[1], row[2]);
            vtr H(row[3], row[4], row[5]);

            // Ordered, thread-safe assignment
            E_fieldSeries[i][t] = E;
            H_fieldSeries[i][t] = H;
        }
    }

    // Print summary
    if (!E_fieldSeries.empty())
    {
        std::cout << "Loaded E/H fields for " << E_fieldSeries.size()
                  << " probes across " << E_fieldSeries[0].size() << " time steps.\n";
    }
    else
    {
        std::cerr << "[Error] No field data loaded.\n";
    }
}


/*
Basic Workflow for FFTW3

1. Allocate input/output memory
--> Use fftwf_malloc() for aligned memory (important for SIMD)

2. Create a plan
A plan tells FFTW how to compute the FFT efficiently for a specific input size and stride.
--> fftwf_plan plan = fftwf_plan_dft_r2c_1d(N, in, out, FFTW_ESTIMATE);

3. Execute the plan
fftwf_execute(plan);

4. Destroy the plan
fftwf_destroy_plan(plan);

5. Free the Memory
fftwf_free(in); fftwf_free(out);

*/

#include <iostream>
#include <iomanip>

void computeFieldFFT(const FieldSeries3D& timeSeries, FFTSeries3D& fftSeries)
{
    int numProbes = timeSeries.size();
    if (numProbes == 0) return;

    int numTimeSamples = timeSeries[0].size();

    int Npad = 4 * numTimeSamples;  // zero-padding factor (e.g., 4x)
    int numFreq = Npad / 2 + 1;

    fftSeries.resize(numProbes);

    fftwf_init_threads();
    fftwf_plan_with_nthreads(1);  // Use 1 thread per plan creation

    for (int p = 0; p < numProbes; ++p)
    {
        fftSeries[p].resize(numFreq);

        float* inX = (float*)fftwf_malloc(sizeof(float) * Npad);
        float* inY = (float*)fftwf_malloc(sizeof(float) * Npad);
        float* inZ = (float*)fftwf_malloc(sizeof(float) * Npad);

        fftwf_complex* outX = (fftwf_complex*)fftwf_malloc(sizeof(fftwf_complex) * numFreq);
        fftwf_complex* outY = (fftwf_complex*)fftwf_malloc(sizeof(fftwf_complex) * numFreq);
        fftwf_complex* outZ = (fftwf_complex*)fftwf_malloc(sizeof(fftwf_complex) * numFreq);

        for (int t = 0; t < numTimeSamples; ++t)
        {
            inX[t] = timeSeries[p][t].getx();
            inY[t] = timeSeries[p][t].gety();
            inZ[t] = timeSeries[p][t].getz();
        }
        for (int t = numTimeSamples; t < Npad; ++t)
        {
            inX[t] = 0.0f;
            inY[t] = 0.0f;
            inZ[t] = 0.0f;
        }

        fftwf_plan planX = fftwf_plan_dft_r2c_1d(Npad, inX, outX, FFTW_ESTIMATE);
        fftwf_plan planY = fftwf_plan_dft_r2c_1d(Npad, inY, outY, FFTW_ESTIMATE);
        fftwf_plan planZ = fftwf_plan_dft_r2c_1d(Npad, inZ, outZ, FFTW_ESTIMATE);

        fftwf_execute(planX);
        fftwf_execute(planY);
        fftwf_execute(planZ);

        for (int f = 0; f < numFreq; ++f)
        {
            cVtr cv;
            cv.setcvtr(
                Complex(outX[f][0], outX[f][1]),
                Complex(outY[f][0], outY[f][1]),
                Complex(outZ[f][0], outZ[f][1])
            );
            fftSeries[p][f] = cv;
        }

        fftwf_destroy_plan(planX);
        fftwf_destroy_plan(planY);
        fftwf_destroy_plan(planZ);
        fftwf_free(inX); fftwf_free(inY); fftwf_free(inZ);
        fftwf_free(outX); fftwf_free(outY); fftwf_free(outZ);

        // Update textual progress
        float progress = (float)(p + 1) / numProbes * 100.0f;
        std::cout << "\r[";
        int barWidth = 50;
        int pos = progress / 100.0f * barWidth;
        for (int i = 0; i < barWidth; ++i)
            std::cout << (i < pos ? "=" : (i == pos ? ">" : " "));
        std::cout << "] " << std::fixed << std::setprecision(1) << progress << "%";
        std::cout.flush();
    }

    std::cout << "\nDone computing FFTs." << std::endl;
    fftwf_cleanup_threads();
}




struct BandAnalysisResult {
    int idx_min;
    int idx_max;
    double fmin_Hz;
    double fmax_Hz;
    int num_points;
    bool valid;
};

BandAnalysisResult analyzeFFTAmplitudeBand(
    const std::vector<cVtr>& fftProbe,
    const std::vector<double>& freqAxis
) {
    int N = fftProbe.size();
    std::vector<double> magnitudes(N);

    double peak = 0.0;



    for (int i = 0; i < N; ++i)
    {
        Complex cx = fftProbe[i].getx();
        Complex cy = fftProbe[i].gety();
        Complex cz = fftProbe[i].getz();

        double mag = std::sqrt(
            std::norm(cx) + std::norm(cy) + std::norm(cz)
        );
        magnitudes[i] = mag;
        if (mag > peak) peak = mag;
    }


    std::ofstream fout("fft_spectrum.csv");
    fout << "Frequency_Hz,Magnitude\n";
    for (int i = 0; i < N; ++i)
    {
        fout << freqAxis[i] << "," << magnitudes[i] << "\n";
    }
    fout.close();
    std::cout << "[Info] FFT spectrum saved to fft_spectrum.csv\n";



    double threshold = 0.05 * peak;
    int idx_min = -1, idx_max = -1;

    for (int i = 0; i < N; ++i) {
        if (magnitudes[i] > threshold) {
            if (idx_min == -1) idx_min = i;
            idx_max = i;
        }
    }

    BandAnalysisResult result;
    if (idx_min != -1 && idx_max != -1) 
    {
        result.idx_min = idx_min;
        result.idx_max = idx_max;
        result.fmin_Hz = freqAxis[idx_min];
        result.fmax_Hz = freqAxis[idx_max];
        result.num_points = idx_max - idx_min + 1;
        result.valid = true;

        std::cout << "Frequency Band: " << result.fmin_Hz / 1e9 << " GHz to " << result.fmax_Hz  / 1e9 << " GHz\n";
        std::cout << "Number of points in band: " << result.num_points << "\n";
        std::cout << "Peak Magnitude: " << peak << "\n";


    } 
    else 
    {
        std::cout << "No significant frequency band found.\n";
        result = { -1, -1, 0.0, 0.0, 0, false };
    }



    return result;
}




std::vector<double> computeFreqAxis(int numTimeSamples, double dt)
{
    int Npad = 4 * numTimeSamples;
    int numFreq = Npad / 2 + 1;
    std::vector<double> freqAxis(numFreq);
    double fs = 1.0 / dt;  // Sampling frequency

    for (int k = 0; k < numFreq; ++k)
        freqAxis[k] = k * fs / Npad;  // f_k = k * (fs / N)

    return freqAxis;
}






void writeCurrents(const std::string& filename, const current2D& current)
{

    int Num_tri = current.size();  // Number of triangles

    std::ofstream fid(filename);
    for (int t = 0; t < Num_tri; ++t) 
    {
        for (int n = 0; n < 3; ++n) 
        {
            cVtr cv = current[t][n];  // Get the first node's current
            fid << cv.getx().real() << " " << cv.getx().imag() << "\n";  // Write real and imaginary parts
            fid << cv.gety().real() << " " << cv.gety().imag() << "\n";  // Write real and imaginary parts
            fid << cv.getz().real() << " " << cv.getz().imag() << "\n";  // Write real and imaginary parts
        }
        fid << "\n";  // Newline after each node
    }
    fid.close();
}







std::pair<double, double> process_RCS(
    const current2D& F_curJ,
    const current2D& F_curM,
    double FREQ,
    const std::string& FREQ_STR,
    const std::string& project_name,
    const std::string& outfile,
    double THETA_sc,
    double PHI_sc,
    int writeMode,
    int output_opt)
{

    std::string current_dir = fs::current_path();
    std::string freq_dir = current_dir + "/freq/FREQ" + FREQ_STR;
    fs::create_directories(freq_dir);
    std::cout << "Working Folder = " << freq_dir << std::endl;
    fs::current_path(freq_dir);

    // Write .curJ and .curM
    writeCurrents(outfile + ".curJ", F_curJ);
    writeCurrents(outfile + ".curM", F_curM);

    // Write .region file
    std::ofstream reg(outfile + ".region");
    reg << "1\n";
    reg << "0 FEBI\n";
    reg << "0 FEBI " << outfile << "\n";
    reg << "Coupling\n";
    reg.close();

    // Copy geometry and binary
    fs::copy(current_dir + "/" + project_name + "_out.tri", freq_dir + "/" + outfile + ".tri", fs::copy_options::overwrite_existing);
    fs::copy(current_dir + "/n2f_main", freq_dir + "/n2f_main", fs::copy_options::overwrite_existing);

    // Run far-field computation
    // Projectname freq_in_MHz centerX centerY centerZ numTheta numPhi mag_or_imaginary radiation_or_scattering
    if (writeMode == 0) 
    {
        std::string cmd_n2f = "./n2f_main " + outfile + " " + std::to_string(int(FREQ)) + " 0 0 0 180 360 " + std::to_string(output_opt)  + " 1";
        std::system(cmd_n2f.c_str());
    } else if (writeMode == 1) 
    {
        std::string cmd_n2f = "./n2f_main " + outfile + " " + std::to_string(int(FREQ)) + " 0 0 0 180 4 " + std::to_string(output_opt)  + " 1";
        std::system(cmd_n2f.c_str());
    } else if (writeMode == 2) 
    {
        std::string cmd_n2f = "./n2f_main " + outfile + " " + std::to_string(int(FREQ)) + " 0 0 0 2 360 " + std::to_string(output_opt)  + " 1";
        std::system(cmd_n2f.c_str());
    } 

    std::system(("emsurftranslator -s " + outfile).c_str());

    std::cout << "\n\n==== Process Farfield Result ====\n\n";
    std::system(("sed -i 's/  / /g' " + outfile + ".cs").c_str());

    // Parse .cs file
    std::ifstream csfile(outfile + ".cs");
    std::vector<std::tuple<double, double, double, double>> rcs_data;
    std::string line;
    std::getline(csfile, line); // skip header
    while (std::getline(csfile, line)) {
        std::istringstream iss(line);
        double theta, phi, rcs_v, rcs_h;
        if (iss >> theta >> phi >> rcs_v >> rcs_h) {
            rcs_data.emplace_back(theta, phi, rcs_v, rcs_h);
        }
    }
    csfile.close();

    fs::current_path(current_dir); // Go back to root dir

    auto it = std::find_if(rcs_data.begin(), rcs_data.end(), [&](auto& row) {
        return std::get<0>(row) == THETA_sc && std::get<1>(row) == PHI_sc;
    });

    if (it != rcs_data.end()) {
        return {std::get<2>(*it), std::get<3>(*it)};
    } else {
        std::cerr << "Requested (theta, phi) RCS not found.\n";
        return {0.0, 0.0};
    }
}






















// Sample usage and test
int main(int argc, char *argv[])
{

        // Computation Time Start and End
        tms tmsStart, tmsEnd;
        times(&tmsStart);

        // Project name
        char prjName[180];
        
        // Scattering directions
        int Theta_sc, Phi_sc;
        
        int output_opt;  // Output format
        double dt;  // Simulation mode
        int step;

        int writeMode;   // writeMode 0: Full  |   1: Principal Phi cuts = 0 cut / 90 cut FULL   |   2: Theta = 90 cut



        // Read input parameters
        if (argc == 8)
        {
            strcpy( prjName, argv[1] );
            dt         = atof(argv[2]);
            step       = atoi(argv[3]);
            Theta_sc   = atoi(argv[4]);
            Phi_sc     = atoi(argv[5]);
            writeMode  = atoi(argv[6]);
            output_opt = atoi(argv[7]);
        }
        else
        {
        std::cout << "Usage:\n";
        std::cout << "  ./program <ProjectName> <dt> <Theta_sc> <Phi_sc> <writeMode> <output_opt>\n\n";
                
        std::cout << "Where:\n";
        std::cout << "  <ProjectName>     = Name of the project (string)\n";
        std::cout << "  <dt>              = Time interval in seconds\n";
        std::cout << "  <step>            = Step in between samples\n";
        std::cout << "  <Theta_sc>        = Scattering angle in theta (deg)\n";
        std::cout << "  <Phi_sc>          = Scattering angle in phi (deg)\n";
        std::cout << "  <writeMode>       = 0 (Full), 1 (Principal Theta cuts), 2 (Principal Phi cuts)\n";
        std::cout << "  <output_opt>      = 0 (magnitude), 1 (real & imag)\n";

        exit(1);
    }
        

    // Set center of origin
    vtr origin;
    origin.setvtr( 0.0, 0.0, 0.0 );

    
    

    OutputSurfMesh outputMesh;

    // Read the mesh from .tri file
    char triName[256];
    sprintf(triName, "./%s_out.tri", prjName);
    std::cout << "--------------------" << std::endl;
    std::cout << "Reading Tri surface mesh " << triName << std::endl;
    outputMesh.readFromFile(triName);
    std::cout << "--------------------" << std::endl;
    std::cout << "Compute Normals " << std::endl;      
    outputMesh.computeTriangleNormals();
    std::cout << "--------------------" << std::endl;
    outputMesh.printSummary();
    std::cout << "--------------------" << std::endl;

    // Store the nodes of the triangles
    int num_nodes = outputMesh.num_nodes;
    int numFiles = countCSVFiles("./PROBES_sc");
    std::cout << "Number of Nodes = " << num_nodes << std::endl;    
    std::cout << "Number of Files = " << numFiles << std::endl;    



    
    // ------------------------------ //
    //   READ FIELDS AT THE PROBES    //
    // ------------------------------ //
    
    // Read Scattered Field
    FieldSeries3D E_fields_sc(num_nodes, std::vector<vtr>(numFiles));
    FieldSeries3D H_fields_sc(num_nodes, std::vector<vtr>(numFiles));
       
    loadSeparatedProbeFields(
        "./PROBES_sc",   // Folder
        "Probes_sphere",     // Base name
        0,                   // Start time
        step,                   // Increment
        numFiles,            // Number of files
        E_fields_sc,
        H_fields_sc
    );


    // Read Incident Field
    FieldSeries3D E_fields_inc(num_nodes, std::vector<vtr>(numFiles));
    FieldSeries3D H_fields_inc(num_nodes, std::vector<vtr>(numFiles));
    loadSeparatedProbeFields(
        "./PROBES_inc",   // Folder
        "Probes_sphere",     // Base name
        0,                   // Start time
        step,                   // Increment
        numFiles,            // Number of files         
        E_fields_inc,
        H_fields_inc
    );
    

    // -------------------------------------- //
    //   Perform FFT of time domain fields    //
    // -------------------------------------- //
    FFTSeries3D E_fields_sc_fft, H_fields_sc_fft;
    FFTSeries3D E_fields_inc_fft;
    E_fields_sc_fft.resize(num_nodes);
    H_fields_sc_fft.resize(num_nodes);
    E_fields_inc_fft.resize(num_nodes);

    std::cout << "Performing FFT on scattered Efields..." << std::endl;
    computeFieldFFT(E_fields_sc, E_fields_sc_fft);
    std::cout << "Performing FFT on scattered Hfields..." << std::endl;
    computeFieldFFT(H_fields_sc, H_fields_sc_fft);
    std::cout << "Performing FFT on Incident Efields..." << std::endl;
    computeFieldFFT(E_fields_inc, E_fields_inc_fft);


    int numTime = E_fields_inc[0].size();
    std::ofstream fout("probe0_incident.csv");
    fout << "TimeStep,Ex,Ey,Ez\n";
    for (int t = 0; t < numTime; ++t)
    {
        fp_t inX = E_fields_inc[0][t].getx();
        fp_t inY = E_fields_inc[0][t].gety();
        fp_t inZ = E_fields_inc[0][t].getz();
        fout << t << "," << inX << "," << inY << "," << inZ << "\n";
    }
    fout.close();
    std::cout << "[Info] Probe 0 time series written to probe0_timeseries.csv\n";


    // Clear the original time domain fields to free memory
    E_fields_sc.clear();
    H_fields_sc.clear();
    E_fields_inc.clear();    
    H_fields_inc.clear();    

    // --------------------------------------------------------------- //
    //   Normalization between scattered fields and incident fields    //
    // --------------------------------------------------------------- //
    
    std::cout << "Compute frequency axis..." << std::endl;
    int numTimeSamples = E_fields_inc[0].size();
    std::vector<double> freqAxis = computeFreqAxis(numTimeSamples, dt);

    std::cout << "Analyzing FFT Amplitude Band..." << std::endl;
    auto band_results = analyzeFFTAmplitudeBand(E_fields_inc_fft[0], freqAxis);

    // Allocate normalized output fields
    FFTSeries3D E_fields_sc_fft_norm(num_nodes);
    FFTSeries3D H_fields_sc_fft_norm(num_nodes);

    // Initialize normalized fields to zero
    for (auto& v : E_fields_sc_fft_norm)
        v.resize(freqAxis.size());
    for (auto& v : H_fields_sc_fft_norm)
        v.resize(freqAxis.size());

    if (!band_results.valid) 
    {
        std::cerr << "[Warning] Invalid FFT band — skipping normalization." << std::endl;
    } 
    else 
    {
        std::cout << "Normalizing scattered E-fields within band..." << std::endl;
    
        // Parallelization across nodes and frequency bins
        #pragma omp parallel for
        for (int n = 0; n < num_nodes; ++n)
        {
            for (int f = band_results.idx_min; f <= band_results.idx_max; ++f)
            {
                const cVtr& E_inc = E_fields_inc_fft[n][f];
                const cVtr& E_scat = E_fields_sc_fft[n][f];
                const cVtr& H_scat = H_fields_sc_fft[n][f];
    
                double inc_mag = std::sqrt(
                    std::norm(E_inc.getx()) +
                    std::norm(E_inc.gety()) +
                    std::norm(E_inc.getz())
                );
    
                if (inc_mag > 1e-12)
                {
                    cVtr E_norm = E_scat / inc_mag;
                    cVtr H_norm = H_scat / inc_mag;
                    E_fields_sc_fft_norm[n][f] = E_norm;
                    H_fields_sc_fft_norm[n][f] = H_norm;
                }
                else
                {
                    cVtr zero;
                    zero.setcvtr(0, 0, 0);
                    E_fields_sc_fft_norm[n][f] = zero;
                    H_fields_sc_fft_norm[n][f] = zero;
                }
            }
        }
    }

    E_fields_inc_fft.clear();  // Free memory for incident fields
    H_fields_sc_fft.clear();   // Free memory for scattered fields
    H_fields_sc_fft.clear();   // Free memory for scattered fields


    // ---------------------------------- //
    //   Compute the tangential fields    //
    // ---------------------------------- //

    std::cout << "Allocating curJ and curM..." << std::endl;

    // Assuming number of frequency points
    int numFreq = E_fields_sc_fft_norm[0].size();

    // ✅ Step 1: Allocation of 3D current arrays    
    current3D curJ(numFreq);
    current3D curM(numFreq);
    
    for (int f = 0; f < numFreq; ++f) 
    {
        curJ[f].resize(outputMesh.num_triangles);
        curM[f].resize(outputMesh.num_triangles);
        for (int t = 0; t < outputMesh.num_triangles; ++t) 
        {
            curJ[f][t].resize(3);  // 3 local nodes
            curM[f][t].resize(3);
        }
    }


    // ✅ Step 2: Compute the tangential fields
    std::cout << "Computing tangential fields..." << std::endl;
    #pragma omp parallel for
    for (int t = 0; t < outputMesh.num_triangles; ++t)
    {
        std::vector<int> tri_nodes = outputMesh.getTriangle(t);
        std::vector<double> normal_d = outputMesh.getNormal(t);
        vtr n(normal_d[0], normal_d[1], normal_d[2]);  // unit normal
    
        for (int j = 0; j < 3; ++j)
        {
            int nodeIdx = tri_nodes[j];
    
            for (int f = 0; f < numFreq; ++f)
            {
                const cVtr& E = E_fields_sc_fft_norm[nodeIdx][f];
                const cVtr& H = H_fields_sc_fft_norm[nodeIdx][f];
    
                // M = -n × E = E × n
                cVtr M_vec = E.cross(n);
                // J = n × H = -H × n
                cVtr J_vec = H.cross(n) * (-1.0f);
    
                curM[f][t][j] = M_vec;
                curJ[f][t][j] = J_vec;
            }
        }
    }
    
    // clear up fft data
    E_fields_sc_fft_norm.clear();  // Free memory for normalized fields
    H_fields_sc_fft_norm.clear();  // Free memory for normalized fields

    std::cout << "Tangential fields computed." << std::endl;
    
    

    // --------------------------------- //
    //   Fast Near to Far Computation    //
    // --------------------------------- //


    std::vector<double> freqList;
    std::vector<double> rcsVList;
    std::vector<double> rcsHList;



    // Compute Far Field 
    for (int f = band_results.idx_min; f <= band_results.idx_max; ++f) 
    {
        std::cout << "Processing frequency " 
        << std::fixed << std::setprecision(3) 
        << freqAxis[f] / 1e9 << " GHz" << std::endl;
    
        double freq = freqAxis[f] / 1e6;
        std::string FREQ_STR = std::to_string(int(freq)); 
        std::string project_name(prjName);
        std::string outfile = "ff_" + FREQ_STR;
    

        // Run Near to Far field computation
        auto [rcs_v, rcs_h] = process_RCS( curJ[f], curM[f], freq, FREQ_STR, project_name, outfile, Theta_sc, Phi_sc, writeMode, output_opt); 

        
        // Collect data
        freqList.push_back(freq/1e3);
        rcsVList.push_back(rcs_v);
        rcsHList.push_back(rcs_h);
    }
    
    // Write RCS summary to CSV file
    rapidcsv::Document doc("", rapidcsv::LabelParams(0, -1));
    doc.InsertColumn(0, freqList, "Frequency_MHz");
    doc.InsertColumn(1, rcsVList, "RCS_V");
    doc.InsertColumn(2, rcsHList, "RCS_H");    
    doc.Save("rcs_summary.csv");
    


    return 0;
}