How can I make the plot smooth?

If I plot this data using SYSTAT application, it looks like the following:

In ChatGPT, it looks like the following:

However, when I plot it using my C# application, it looks like the following:

Can you tell me what I am doing wrong?

N.B. The C# source code is high-level abstracted source code.

Residue   ,Density        ,Tau0           
10,0.001,21.937
10,0.001,22.04
10,0.001,22.032
10,0.001,21.962
10,0.001,21.845
10,0.001,21.929
10,0.001,21.794
10,0.001,21.918
10,0.001,21.877
10,0.001,21.81
10,0.001,21.832
10,0.001,21.872
10,0.001,21.813
10,0.001,21.608
10,0.001,21.679
10,0.005,22.067
10,0.005,22.037
10,0.005,21.906
10,0.005,21.941
10,0.005,21.964
10,0.005,21.871
10,0.005,21.938
10,0.005,21.918
10,0.005,21.941
10,0.005,21.752
10,0.005,21.766
10,0.005,21.821
10,0.005,21.757
10,0.005,21.699
10,0.005,21.776
10,0.01,22.231
10,0.01,22.228
10,0.01,22.116
10,0.01,22.131
10,0.01,22.166
10,0.01,22.155
10,0.01,21.951
10,0.01,22.003
10,0.01,21.996
10,0.01,22.126
10,0.01,21.981
10,0.01,21.913
10,0.01,21.984
10,0.01,21.947
10,0.01,21.889
15,0.001,55.011
15,0.001,54.892
15,0.001,54.325
15,0.001,54.349
15,0.001,54.554
15,0.001,54.288
15,0.001,54.213
15,0.001,53.985
15,0.001,54.296
15,0.001,54.29
15,0.001,54.187
15,0.001,53.237
15,0.001,53.908
15,0.001,53.524
15,0.001,52.545
15,0.005,55.073
15,0.005,55.296
15,0.005,55.072
15,0.005,54.901
15,0.005,54.969
15,0.005,54.625
15,0.005,54.299
15,0.005,53.906
15,0.005,54.336
15,0.005,53.949
15,0.005,54.12
15,0.005,54.243
15,0.005,53.788
15,0.005,53.831
15,0.005,53.746
15,0.01,55.233
15,0.01,55.165
15,0.01,55.057
15,0.01,54.919
15,0.01,54.849
15,0.01,55.066
15,0.01,55.113
15,0.01,54.624
15,0.01,54.419
15,0.01,54.389
15,0.01,54.075
15,0.01,54.335
15,0.01,53.77
15,0.01,54.248
15,0.01,53.563
25,0.001,164.724
25,0.001,164.99
25,0.001,163.518
25,0.001,164.708
25,0.001,162.769
25,0.001,162.927
25,0.001,162.678
25,0.001,163.869
25,0.001,162.71
25,0.001,161.045
25,0.001,161.379
25,0.001,161.428
25,0.001,161.531
25,0.001,159.493
25,0.001,160.823
25,0.005,167.892
25,0.005,166.525
25,0.005,165.384
25,0.005,164.054
25,0.005,163.825
25,0.005,163.319
25,0.005,161.626
25,0.005,161.139
25,0.005,158.917
25,0.005,160.506
25,0.005,161.778
25,0.005,160.07
25,0.005,159.091
25,0.005,160.715
25,0.005,157.838
25,0.01,167.243
25,0.01,166.138
25,0.01,164.303
25,0.01,167.051
25,0.01,164.707
25,0.01,163.833
25,0.01,164.682
25,0.01,163.755
25,0.01,163.913
25,0.01,162.615
25,0.01,163.848
25,0.01,162.233
25,0.01,160.745
25,0.01,163.592
25,0.01,159.967
using SikorskiLibMemoryLess;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace NversusTauPlotFromCSVNamespace
{
    public class CallBackClass
    {
        public static void Run()
        {
            try
            {
                Command actualImageCommand = CommandParserForXml.GetActualCommand("--image_size");
                if (actualImageCommand == null || actualImageCommand.DefaultArguments.Count < 2)
                {
                    throw new ArgumentException("Invalid image size command.");
                }

                int imageWidth = Convert.ToInt32(actualImageCommand.DefaultArguments[0]);
                int imageHeight = Convert.ToInt32(actualImageCommand.DefaultArguments[1]);

                DataPlotter plotter = new DataPlotter
                {
                    ImageTitle = "Density vs. relaxation time (3D vector case)",
                    XAxisTitle = "d (density)",
                    YAxisTitle = "τ0 (relaxation time)",
                    IsLogY = false,
                    IsLogX = true,
                    IsSymbolVisible = true,
                    IsLegendVisible = true
                };

                Command outputDirCommand = CommandParserForXml.GetActualCommand("--output");
                if (outputDirCommand == null || outputDirCommand.DefaultArguments.Count < 2)
                {
                    throw new ArgumentException("Invalid output directory command.");
                }

                string outputDir = outputDirCommand.DefaultArguments[0];
                string outputFileName = outputDirCommand.DefaultArguments[1];

                Command actualFileCommand = CommandParserForXml.GetActualCommand("--input");
                if (actualFileCommand == null || actualFileCommand.DefaultArguments.Count < 2)
                {
                    throw new ArgumentException("Invalid input file command.");
                }

                string inputFilePath = actualFileCommand.DefaultArguments[0];
                string chainLengths = actualFileCommand.DefaultArguments[1];

                var csv = FileReaderMemoryLess.ReadCSV(inputFilePath);
                if (csv == null || csv.Count() == 0)
                {
                    throw new ArgumentException("CSV file is empty or invalid.");
                }

                var array = ConvertHelper.ToDoubleArray(chainLengths);
                List<double> lengthList = new List<double>(array);

                ListPairsMemoryLess listPairs = new ListPairsMemoryLess();

                foreach (var length in lengthList)
                {
                    List<double> xList = new List<double>();
                    List<double> yList = new List<double>();

                    for (int i = 1; i < csv.Count(); i++) // Skip header row
                    {
                        try
                        {
                            List<string> columns = csv.ElementAt(i);
                            double residueLength = Convert.ToDouble(columns[0]);
                            double density = Convert.ToDouble(columns[3]); // Density column
                            double tao0 = Convert.ToDouble(columns[6]); // Tau0 column

                            if (residueLength == length)
                            {
                                xList.Add(density);
                                yList.Add(tao0);
                            }
                        }
                        catch (Exception ex)
                        {
                            Console.WriteLine($"Error parsing line {i}: {ex.Message}");
                        }
                    }

                    listPairs.Add($"{length}", xList, yList);
                    //listPairs.SortByXList(); // Sort after adding the pairs
                    plotter.AddCurve($"N = {length}", xList, yList, UniqueColors.GetNextColor());

                    Console.WriteLine($"N:{length}, xLen:{xList.Count}, yLen:{yList.Count}");
                }

                Console.WriteLine("Saving plot");
                plotter.SavePlot(outputDir, $"{outputFileName}.png");
                Console.WriteLine($"Plot saved in {outputDir}");

                plotter.ShowDialog();
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error: {ex.Message}");
                Console.WriteLine(ex.StackTrace);
            }

            ConsoleUtils.Wait();
        }
    }
}

Trang chủ Giới thiệu Sinh nhật bé trai Sinh nhật bé gái Tổ chức sự kiện Biểu diễn giải trí Dịch vụ khác Trang trí tiệc cưới Tổ chức khai trương Tư vấn dịch vụ Thư viện ảnh Tin tức - sự kiện Liên hệ Chú hề sinh nhật Trang trí YEAR END PARTY công ty Trang trí tất niên cuối năm Trang trí tất niên xu hướng mới nhất Trang trí sinh nhật bé trai Hải Đăng Trang trí sinh nhật bé Khánh Vân Trang trí sinh nhật Bích Ngân Trang trí sinh nhật bé Thanh Trang Thuê ông già Noel phát quà Biểu diễn xiếc khỉ Xiếc quay đĩa Dịch vụ tổ chức sự kiện 5 sao Thông tin về chúng tôi Dịch vụ sinh nhật bé trai Dịch vụ sinh nhật bé gái Sự kiện trọn gói Các tiết mục giải trí Dịch vụ bổ trợ Tiệc cưới sang trọng Dịch vụ khai trương Tư vấn tổ chức sự kiện Hình ảnh sự kiện Cập nhật tin tức Liên hệ ngay Thuê chú hề chuyên nghiệp Tiệc tất niên cho công ty Trang trí tiệc cuối năm Tiệc tất niên độc đáo Sinh nhật bé Hải Đăng Sinh nhật đáng yêu bé Khánh Vân Sinh nhật sang trọng Bích Ngân Tiệc sinh nhật bé Thanh Trang Dịch vụ ông già Noel Xiếc thú vui nhộn Biểu diễn xiếc quay đĩa Dịch vụ tổ chức tiệc uy tín Khám phá dịch vụ của chúng tôi Tiệc sinh nhật cho bé trai Trang trí tiệc cho bé gái Gói sự kiện chuyên nghiệp Chương trình giải trí hấp dẫn Dịch vụ hỗ trợ sự kiện Trang trí tiệc cưới đẹp Khởi đầu thành công với khai trương Chuyên gia tư vấn sự kiện Xem ảnh các sự kiện đẹp Tin mới về sự kiện Kết nối với đội ngũ chuyên gia Chú hề vui nhộn cho tiệc sinh nhật Ý tưởng tiệc cuối năm Tất niên độc đáo Trang trí tiệc hiện đại Tổ chức sinh nhật cho Hải Đăng Sinh nhật độc quyền Khánh Vân Phong cách tiệc Bích Ngân Trang trí tiệc bé Thanh Trang Thuê dịch vụ ông già Noel chuyên nghiệp Xem xiếc khỉ đặc sắc Xiếc quay đĩa thú vị
Trang chủ Giới thiệu Sinh nhật bé trai Sinh nhật bé gái Tổ chức sự kiện Biểu diễn giải trí Dịch vụ khác Trang trí tiệc cưới Tổ chức khai trương Tư vấn dịch vụ Thư viện ảnh Tin tức - sự kiện Liên hệ Chú hề sinh nhật Trang trí YEAR END PARTY công ty Trang trí tất niên cuối năm Trang trí tất niên xu hướng mới nhất Trang trí sinh nhật bé trai Hải Đăng Trang trí sinh nhật bé Khánh Vân Trang trí sinh nhật Bích Ngân Trang trí sinh nhật bé Thanh Trang Thuê ông già Noel phát quà Biểu diễn xiếc khỉ Xiếc quay đĩa
Thiết kế website Thiết kế website Thiết kế website Cách kháng tài khoản quảng cáo Mua bán Fanpage Facebook Dịch vụ SEO Tổ chức sinh nhật