c# array [][] vs [,]

One is an array of arrays, and one is a 2d array. The former can be jagged, the latter is uniform.

That is, a double[][] can validly be:
double[][] x = new double[5][];

x[0] = new double[10];
x[1] = new double[5];
x[2] = new double[3];
x[3] = new double[100];
x[4] = new double[1];

Because each entry in the array is a reference to an array of double. With a jagged array, you can do an assignment to an array like you want in your second example:
x[0] = new double[13];

On the second item, because it is a uniform 2d array, you can't assign a 1d array to a row or column, because you must index both the row and column, which gets you down to a single double:
double[,] ServicePoint = new double[10,9];

ServicePoint[0]... // <-- meaningless, a 2d array can't use just one index.

UPDATE:

To clarify based on your question, the reason your #1 had a syntax error is because you had this:
double[][] ServicePoint = new double[10][9];

And you can't specify the second index at the time of construction. The key is that ServicePoint is not a 2d array, but an 1d array (of arrays) and thus since you are creating a 1d array (of arrays), you specify only one index:
double[][] ServicePoint = new double[10][];

Then, when you create each item in the array, each of those are also arrays, so then you can specify their dimensions (which can be different, hence the term jagged array):
ServicePoint[0] = new double[13];
ServicePoint[1] = new double[20];

Hope that helps!

Accord 를 이용한 엑셀 파일 import 하는 코드

public double[][] Inputs         ;
public int[]      Outputs           ;


public void ImportExcelData()
        {
            OpenFileDialog of = new OpenFileDialog();
            if (of.ShowDialog() == DialogResult.OK)
            {
                TDataTable = new ExcelReader(of.FileName).GetWorksheet("Classification - Yin Yang");
            }
            double[][] input  = TDataTable.ToArray("X", "Y"); // Column Header Name.
            int[]      output = TDataTable.Columns["G"].ToArray();
            ScatterplotBox.Show("TT", input, output).Hold();
            WriteData2Field(input, output);
        }

[C#] 파일 경로 불러오는법

경로는 다음과 같이 되어야 된다.
"C:\\Users\\SJW\\Desktop\\Local project\\알고리즘 예제\\Logistic\\LogisticClassification\\LogisticClassification\\data\\examples.xls"


string fileName = "examples.xls";


1번째 방법
string path = Path.Combine(Environment.CurrentDirectory, @"data\", fileName); // 여기선 디버그 폴더안의 example.xls를 가져올떄
           
2번째 방법
string path = new DirectoryInfo(Environment.CurrentDirectory).Parent.Parent.FullName; // bin 폴더 전,즉 프로젝트메인 폴더까지
string combinedpath = Path.Combine(path, "data", fileName);
TDataTable = new ExcelReader(combinedpath).GetWorksheet("Classification - Yin Yang");


3번째
using System.Windows.Forms; 을 사용해서 (레퍼런스에 추가 필수 )


if (of.ShowDialog() == DialogResult.OK)
            {
                TDataTable = new ExcelReader(of.FileName).GetWorksheet("Classification - Yin Yang");
            
            }


이렇게도 가능하다.

Accord Setting

Install Accrod From Nuget


Need


Accord
Accord.Io
Accord.MachineLearning
Accord.Statics
Accord.Control
Accord.Math

파이썬 행렬생성 numpy.linspace

numpy.linspace(start, stop, num=50, endpoint=True, retstep=False, dtype=None)


>>> np.linspace(2.0, 3.0, num=5)    
array([ 2. , 2.25, 2.5 , 2.75, 3. ])


>>> np.linspace(2.0, 3.0, num=5, endpoint=False)
    array([ 2. , 2.2, 2.4, 2.6, 2.8])


>>> np.linspace(2.0, 3.0, num=5, retstep=True)


    (array([ 2. , 2.25, 2.5 , 2.75, 3. ]), 0.25)




ex )
n = 100
    x = np.linspace(0, 2 * math.pi, n)
    y = np.sin(x) + 0.3 * np.random.randn(n)


x는 1 x 100 의 행렬 (n이 100 이므로)
y는 100의 포인트에 노이즈가 들어간 사인 그래프가 된다.