The name 'cos' does not exist in the current context-CodePudding

I'm trying to derive using the math.net.symbolics library.

I am getting this error: Compiler Error CS0103 The name 'cos' does not exist in the current context

private void Form1_Load(object sender, EventArgs e)
    {
        var x = Expr.Variable("x");
        var func = 2 * x * x - 2 * Trigonometric.Contract(cos(x))   1;     //exc. question: 2 * x * x - 2 * cos(x)   1
        Console.WriteLine("f(x) = "   func.ToString());                     //answer: //4*x 2*sin(x)     

        var derivative = func.Differentiate(x);
        Console.WriteLine("f'(x) = "   derivative.ToString());
    }

CodePudding user response：

The documentation is for F#. it wasn't working because I was writing code in C#.

Problem fixed when I used

x.Cos()

instead of

cos(x)