public static void readDataInt(string value, ref int[][] data, ref DateTime[] timeframe, ref DateTime[] date)
    {
        string inputFile = "D:\temp.csv";
        string[][] temp = null;

        if (File.Exists(inputFile))
        {
            string[] proRataVolumeFile = File.ReadAllLines(inputFile);
            temp = new string[proRataVolumeFile.Length][];

            for (int i = 0; i < proRataVolumeFile.Length; i++)
            {
                temp[i] = proRataVolumeFile[i].Split(',');
            }
        }

              //convert the string to int

        date = new DateTime[temp.Length - 1];
        timeframe = new DateTime[temp[0].Length - 1];
        data = new int[temp.Length - 1][];

        for (int i = 1; i < temp.Length; i++)
        {
            data[i - 1] = new int[temp[i].Length - 1];

            for (int j = 1; j < temp[i].Length; j++)
            {
                if (temp[i][j].Length > 0)
                    data[i - 1][j - 1] = Convert.ToInt32(temp[i][j]);
            }
        }

        for (int i = 1; i < temp.Length; i++)
        {
            date[i - 1] = Convert.ToDateTime(temp[i][0]);
        }

        for (int j = 1; j < temp[0].Length; j++)
        {
            timeframe[j - 1] = DateTime.Parse(temp[0][j]);
        }
    }

void SomeMethod<T>(T[] values) where T : IComparable<T>
{
    // Do stuff here
}

public static void ReadData<T>(string value, ref T[][] data, ref DateTime[] timeframe, ref DateTime[] date) where T : IConvertible
{

dynamic SomeMethod(dynamic[] values)
{
    dynamic result = values[0];
    for (int i = 1; i < values.Length; ++i)
         result = result + values[i]; // You can use normal operators now
    return result;
}

static void Swap<T>(ref T lhs, ref T rhs)
{
  T temp;
  temp = lhs;
  lhs = rhs;
  rhs = temp;
}

int a = 2;
 int b = 3;
 Swap<int>(ref a, ref b);

double a = 2.3;
 double b = 5.7;
 Swap<double>(ref a, ref b);

int[] ints = {1, 2, 3 };
    List<int> listInts = ints.ToList();

    MyMethod<int>(listInts);

    private static void MyMethod<T>(List<T> genericList)
    {
        // do you work
    }

public static void ReadDataInt(string value, out int[][] data,
                         out DateTime[] timeframe, out DateTime[] date)
    {
        ReadData(value, out data, out timeframe, out date, Convert.ToInt32);
    }

    public static void ReadDataDouble(string value, out double[][] data,
                         out DateTime[] timeframe, out DateTime[] date)
    {
        ReadData(value, out data, out timeframe, out date, Convert.ToDouble);
    }

    private static void ReadData<T>(string value, out T[][] data,
                          out DateTime[] timeframe, out DateTime[] date,
                          Func<string, T> converter)
    {
        ...your method goes here with some very minor changes below.

        // Generic instead of int/double
        data = new T[temp.Length - 1][];
        ...
        // Generic instead of int/double
        data[i - 1] = new T[temp[i].Length - 1];
        ...
        // Use a func instead of the hard coded Convert.
        if (temp[i][j].Length > 0)
            data[i - 1][j - 1] = converter(temp[i][j]);