Get the list of filenames in a folder

1) Open PowerShell
2) Navigate to the folder which content you wanna export
3) Type & Enter this command :

Get-Childitem -PAth . > C:\path\where\to\store\the\file\filenames.txt

That's it!

ORACLE PL/SQL ... if dbms_output.put_line('Hello World'); does not work...

If  dbms_output.put_line('Hello World'); in your PL/SQL script does not work, you probably forgot to activate the output in your SQLPLUS.exe or SQL Developer!


To activate the output, enter the following command:


set serveroutput on


Now you can execute your function/procedure:



begin
dbms_output.put_line('Hello World');
end;
/

C#: A Linear Regression example with the NelderMead solver from Microsoft Solver Foundation (MSF)

Given that you installed the Microsoft Solver Foundation (msdn.microsoft.com)
and referenced the MSF dll (Microsoft.Solver.Foundation.dll) in your VisualStudio Project here is a simple code to test the NonLinear solver (aka NelderMead solver)  that ships with the library.

I hope Microsoft will revive this nice library in the future (at the moment the project is abandoned :( )

// here is the code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.SolverFoundation.Common;
using Microsoft.SolverFoundation.Services;
using Microsoft.SolverFoundation.Solvers;

namespace LinearRegressionMSF
{
    class Program
    {

    // We want to get a this line's coefficients back: y = 11.22*x + 77.99
   
        static double[] xData = new double[] { 0, 1, 2, 3, 4, 5, 6, 7 };
        static double[] yData = new double[] { 0 * 11.22 + 77.99, 1 * 11.22 + 77.99, 2 * 11.22 + 77.99, 3 * 11.22 + 77.99, 4 * 11.22 + 77.99, 5 * 11.22 + 77.99, 6 * 11.22 + 77.99, 7 * 11.22 + 77.99 };


        static void Main(string[] args)
        {

            LinearRegressionWithNelderMeadSolver();

            Console.ReadKey();
        }



        private static void LinearRegressionWithNelderMeadSolver()
        {
            // initial values for the two parameters
            double[] pInitial = new double[] { 1, 1 };
           
            // lower and upper limits for the two paramenters           
            double[] pLower = new double[] { -100, -100 };
            double[] pUpper = new double[] { 100, 100 };

            var solution = NelderMeadSolver.Solve(SumOfSquares, pInitial, pLower, pUpper);

            Console.WriteLine(solution.Result);
            Console.WriteLine("solution = {0}", solution.GetSolutionValue(0));
            Console.WriteLine("x = {0}", solution.GetValue(1));
            Console.WriteLine("y = {0}", solution.GetValue(2));
        }


        private static double SumOfSquares(double[] p)
        {
            double q = p[0];
            double m = p[1];

            double dSumOfSquares = 0;

            for (int i = 0; i < xData.Length; ++i)
            {
                dSumOfSquares += Math.Pow(yData[i] - m * xData[i] - q, 2);
            }

            return dSumOfSquares;
        }
    }

}

Entity Framework: Model successfully updated but changes are not available in code

I lost quite some time on this annoying issue that sometimes affects my VisualStudio 2015 with the Devart Oracle Driver for using Entity Framework.

My changes in the database (for example a modification of a view) were reflected ONLY in the entity framework model (after selecting the usual Update Model from Database...) but the modified classes WERE NOT available in the code!

The solution is very simple: "Run Custom Tool"

Select your model file (the one with extension with .edml), right click an choose "Run Custom Tool".

Now the changes to your database are available in your code too.

Source:

https://blog.jongallant.com/2012/08/entity-framework-manual-update/

Where is java on macOS?

Open the terminal and execute the following command:


/usr/libexec/java_home -v 1.7


It will locate the files corresponding to the provided java version.
 
Here the link for Java6 from Apple (useful is you want to install Matlab):

https://support.apple.com/kb/dl1572?locale=en_US

Excel-Files take way too to open [Windows 10 issue on Dell]

This is not strictly speaking a programming issue, but definitely something quite annoying.
On my Windows 10 on my DELL  OptiPlex,  opening an excel file used to take about 30 seconds! It didn't matter if the file was on a local or network folder!
The issue was, in my case, related to the Audio Driver. Yes! An issue with Excel was related to the Realtek Audio Driver!

Anyway, here is the Dell's post:

http://www.dell.com/support/article/de/de/debsdt1/sln306701/slow-performance-issues-in-excel-when-opening-saved-files?lang=en

Solution:

Find your Computer Version in http://www.dell.com/support/drivers/home and update your Audio Driver