Csharp/CSharp Tutorial/Data Type/double Calculation

Calculate the radius of a circle given its area using Math function

using System; 
 
class MainClass {    
  public static void Main() {    
    Double r; 
    Double area; 
 
    area = 10.0; 
 
    r = Math.Sqrt(area / 3.1416); 
 
    Console.WriteLine("Radius is " + r); 
  }    
}

Radius is 1.78412203012729

Compute the area of a circle with "double"

using System;  
   
class Circle {   
  public static void Main() {   
    double radius; 
    double area; 
 
    radius = 10.0; 
    area = radius * radius * 3.1416; 
 
    Console.WriteLine("Area is " + area); 
  }   
}

Area is 314.16

Do calculation with double value

using System;
using System.Collections.Generic;
using System.Text;
class Program {
    static void Main(string[] args) {
        double firstNumber, secondNumber;
        string userName;
        userName = "AAA";
        firstNumber = Convert.ToDouble("1.1");
        Console.WriteLine("Now give me another number:");
        secondNumber = Convert.ToDouble(1.2);
        Console.WriteLine("The sum of {0} and {1} is {2}.", firstNumber,
                    secondNumber, firstNumber + secondNumber);
        Console.WriteLine("The result of subtracting {0} from {1} is {2}.",
                    secondNumber, firstNumber, firstNumber - secondNumber);
        Console.WriteLine("The product of {0} and {1} is {2}.", firstNumber,
                    secondNumber, firstNumber * secondNumber);
        Console.WriteLine("The result of dividing {0} by {1} is {2}.",
                    firstNumber, secondNumber, firstNumber / secondNumber);
        Console.WriteLine("The remainder after dividing {0} by {1} is {2}.",
                    firstNumber, secondNumber, firstNumber % secondNumber);
    }
}

double base Fahrenheit and Celsius (Centigrade) Scales

using System;
public class MainClass {
    public static void Main(string[] args) {
        double dFahr = 123.123;
        double dCelsius;
        dCelsius = (dFahr - 32.0) * (5.0 / 9.0);
        Console.WriteLine("Temperature in degrees Celsius = " + dCelsius);
    }
}

doubles and arithmetic operators

class MainClass
{
  public static void Main()
  {
  
    System.Console.WriteLine("10d / 3d = " + 10d / 3d);
    System.Console.WriteLine("10.0 / 3.0 = " + 10.0 / 3.0);
    double doubleValue1 = 10;
    double doubleValue2 = 3;
    System.Console.WriteLine("doubleValue1 / doubleValue2 = " + doubleValue1 / doubleValue2);
  }
}

10d / 3d = 3.33333333333333
10.0 / 3.0 = 3.33333333333333
doubleValue1 / doubleValue2 = 3.33333333333333

Implement the Pythagorean Theorem

using System;  
class MainClass {     
  public static void Main() {     
    double s1 = 3.0; 
    double s2 = 4.0; 
    double hypot; 
 
    hypot = Math.Sqrt(s1*s1 + s2*s2); 
  
    Console.WriteLine("Hypotenuse is " + hypot); 
  }     
}

Hypotenuse is 5

Use the while statement to implement Newton"s method for finding the square root

using System;
public class MainClass {
   public static void Main( ) {
    double epsilon   = 1.0e-9;
    double guess    = 11.0;
    double value = 2;
      double result = ((value / guess) + guess) / 2;
      Console.WriteLine( "Guess Value  = {0}", guess  );
      Console.WriteLine( "Result Value = {0}", result );
      while( Math.Abs(result - guess) > epsilon ) {
          guess = result;
        result = ((value / guess) + guess) / 2;
          Console.WriteLine( "Guess Value  = {0}", guess  );
          Console.WriteLine( "Result Value = {0}", result );
    }
    Console.WriteLine("The approx sqrt of {0} is {1}", value, result );
    }
}

Guess Value  = 11
Result Value = 5.59090909090909
Guess Value  = 5.59090909090909
Result Value = 2.97431633407243
Guess Value  = 2.97431633407243
Result Value = 1.82336988350512
Guess Value  = 1.82336988350512
Result Value = 1.46012001740362
Guess Value  = 1.46012001740362
Result Value = 1.41493521627426
Guess Value  = 1.41493521627426
Result Value = 1.41421374640426
Guess Value  = 1.41421374640426
Result Value = 1.41421356237311
Guess Value  = 1.41421356237311
Result Value = 1.41421356237309
The approx sqrt of 2 is 1.41421356237309