C# / .NET - Math.Sin() method example

Math.Sin is a static method that takes only one parameter and returns an approximation of sine mathematical function.

using System;

public class Program
{
    public static void Main(string[] args)
    {
        Console.WriteLine( Math.Sin( 0                  ) ); //   0 <-     0 degrees
        Console.WriteLine( Math.Sin( 1.5707963267948966 ) ); //  ~1 <-  ~90 degrees ==  PI / 2
        Console.WriteLine( Math.Sin( 3.1415926535897932 ) ); //  ~0 <- ~180 degrees ==  PI
        Console.WriteLine( Math.Sin( 4.71238898038469   ) ); // ~-1 <- ~270 degrees == -PI * (3/2)
        Console.WriteLine( Math.Sin( 6.2831853071795850 ) ); //  ~0 <- ~360 degrees ==  PI * 2

        Console.WriteLine( Math.Sin(-1.5707963267948966 ) ); // ~-1 <- ~-90 degrees == -PI / 2
    }
}

Note: 1.2246467991473532e-16 and -1.133107779529596e-15 should be equal to 0 but they are not because of compuptation precision error.

1. Documentation

namespace System
{
    public static class Math
    {
        // ...
        public static double Sin(double number) { ... }
        // ...
    }
}

2. Working with radians

using System;

public class Program
{
    public static void Main(string[] args)
    {
        double x1 = 0.0;          // beginning of calculation in radians
        double x2 = Math.PI / 2;  // ending of calculation radians

        double dx = Math.PI / 9; // calculation step in degrees

        for (double rad = x1; rad <= x2; rad += dx)
        {
            double y = Math.Sin(rad);
            Console.WriteLine("sin(" + rad + " rad) = " + y);
        }
    }
}

Output: 

sin(0 rad) = 0
sin(0.3490658503988659 rad) = 0.3420201433256687
sin(0.6981317007977318 rad) = 0.6427876096865393
sin(1.0471975511965976 rad) = 0.8660254037844386
sin(1.3962634015954636 rad) = 0.984807753012208

3. Working with degrees

using System;

public class Program
{
    static double CalculateSin(double deg)
    {
        double radians = (Math.PI / 180) * deg;
        return Math.Sin(radians);
    }

    public static void Main(string[] args)
    {
        // Example:

        double x1 = 0.0;  // beginning of calculation in degrees
        double x2 = 90.0; // ending of calculation degrees

        double dx = 15.0;  // calculation step in degrees

        for (double deg = x1; deg <= x2; deg += dx)
        {
            double y = CalculateSin(deg);
            Console.WriteLine("sin(" + deg + " deg) = " + y);
        }
    }
}

Output: 

sin(0 deg) = 0
sin(15 deg) = 0.25881904510252074
sin(30 deg) = 0.49999999999999994
sin(45 deg) = 0.7071067811865476
sin(60 deg) = 0.8660254037844386
sin(75 deg) = 0.9659258262890683
sin(90 deg) = 1

4. Reversed console plot example

using System;
using System.Text;

public class Program
{
    public static void Main(string[] args)
    {
        double x1 = 0.0;      // beginning of sine chart
        double x2 = 2 * 3.14; // end of sine chart

        double dx = 3.14 / 4.0; // x axis step
        double dy = 1.0 / 5.0; // y axis step

        for (double rad = x1; rad < x2; rad += dx)
        {
            double y1 = 0.0;
            double y2 = Math.Sin(rad) + 1;
            StringBuilder line = new StringBuilder();
            for (double y = y1; y < y2; y += dy)
            {
                line.Append(" ");
            }
            Console.WriteLine(line + "+");
        }
    }
}

Output: 

     +
         +
          +
         +
      +
  +
 +
  +

References

1. Sine - Wikipedia