Wednesday, February 8, 2012

Factorial and Fibonacci in Fantom



Here below a little program in Fantom that implements 2 classes (in fact, they are 3 + an extra utility Stopwatch class from my previous post http://carlosqt.blogspot.com/2011/05/stopwatch-class-for-java.html). There is the main class, called Fiborial (Fibo(nnacci)+(Facto)rial) that implements the Fibonacci and the Factorial algorithms in two ways, one Recursive (using recursion) and the other Imperative (using loops and states). The second class is just an instance class that does the same thing, but its there just to show the difference between static and instance classes, and finally the third one (which will not appear in other languages) is the Program class which has the static execution method "main".

You can also find 3 more little examples at the bottom. One prints out the Factorial's Series and Fibonacci's Series, the second one just shows a class that mixes both: static and instance members, and finally the third one that uses different return types (including java.math.BigInteger) for the Factorial method to compare the timing and result.

As with the previous posts, you can copy and paste the code below in your favorite IDE/Editor and start playing and learning with it. This little "working" program will teach you some more basics of the Programming Language.

There are some "comments" on the code added just to tell you what are or how are some features called. In case you want to review the theory, you can read my previous post, where I give a definition of each of the concepts mentioned on the code. You can find it here: http://carlosqt.blogspot.com/2011/01/new-series-factorial-and-fibonacci.html 


The Fiborial Program

// Factorial and Fibonacci in Fantom

using [java] com.carlosqt.util::Stopwatch
using [java] java.math::BigInteger

// static is not a valid class modifier
// Instanced Class
class StaticFiborial 
{
  // (Constant) Static Field  - Static fields must be const - this ensures thread safety  
  private const static Str className
  // Class/Static Constructor/Initializer
  // It is permissible to have multiple static initializers; they run in order of declaration
  static 
  {      
    className = "Static Constructor"  
    echo(className)  
  }
  // Static Method - Factorial Recursive
  static BigInteger factorialR(Int n)      
  {      
    if (n == 1)      
      return BigInteger.ONE  
    else      
      return BigInteger.valueOf(n).multiply(factorialR(n - 1))  
  }
  // Static Method - Factorial Imperative      
  static BigInteger factorialI(Int n)      
  {      
    BigInteger res := BigInteger.ONE  
    for (i := n; i >= 1; i--)      
    {                      
      res = res.multiply(BigInteger.valueOf(i))  
    }      
    return res  
  }
  // Static Method - Fibonacci Recursive      
  static Int fibonacciR(Int n)      
  {      
    if (n < 2)      
      return 1  
    else      
      return fibonacciR(n - 1) + fibonacciR(n - 2)  
  }      
  // Static Method - Fibonacci Imperative      
  static Int fibonacciI(Int n)      
  {                  
    Int pre := 1  
    Int cur := 1  
    Int tmp := 0   
    for (i := 2; i <= n; i++)  
    {      
      tmp = cur + pre  
      pre = cur  
      cur = tmp  
    }      
    return cur    
  }          
  // Class/Static Method - Benchmarking Algorithms      
  static Void benchmarkAlgorithm(Int algorithm, List values)      
  {                  
    Stopwatch timer := Stopwatch()  
    Int testValue := 0 
    BigInteger facTimeResult := BigInteger.ZERO  
    Int fibTimeResult := 0
    // "Switch" Flow Control Statement
    switch (algorithm)    
    {    
      case 1:    
        echo("\nFactorial Imperative:")    
        // "For" Loop Statement    
        for (i := 0; i < values.size; i++)    
        {                            
          testValue = values.get(i)    
          // Taking Time    
          timer.start()    
          facTimeResult = factorialI(testValue)    
          timer.stop()
          // Getting Time    
          echo(" ($testValue) = ${timer.getElapsed()}")    
        }
      case 2:    
        echo("\nFactorial Recursive:")    
        // "While" Loop Statement
        Int i := 0
        while (i < values.size)    
        {                            
          testValue = values.get(i)   
          // Taking Time    
          timer.start()    
          facTimeResult = factorialR(testValue)
          timer.stop()
          // Getting Time    
          echo(" ($testValue) = ${timer.getElapsed()}")    
          i++
        }    
      case 3:    
        echo("\nFibonacci Imperative:")    
        // "While" Loop Statement
        Int i := 0
        while (i < values.size)    
        {
          testValue = values.get(i)    
          // Taking Time    
          timer.start()    
          fibTimeResult = fibonacciI(testValue)    
          timer.stop()    
          // Getting Time    
          echo(" ($testValue) = ${timer.getElapsed()}")    
          i++    
        }    
      case 4:    
        echo("\nFibonacci Recursive:")      
        // "For" Loop Statement    
        for (i := 0; i < values.size; i++)    
        {    
          testValue = values.get(i)
          // Taking Time    
          timer.start()    
          fibTimeResult = fibonacciR(testValue)   
          timer.stop()   
          // Getting Time    
          echo(" ($testValue) = ${timer.getElapsed()}")    
        }    
        default:    
          echo("DONG!")    
    }                    
  }
}


// Instance Class      
class InstanceFiborial      
{      
  // Instance Field      
  private Str className  
  // Instance Constructor      
  new make()      
  {      
      this.className = "Instance Constructor"  
      echo(this.className)  
  }      
  // Instance Method - Factorial Recursive      
  BigInteger factorialR(Int n)      
  {      
      // Calling Static Method      
      return StaticFiborial.factorialR(n)  
  }      
  // Instance Method - Factorial Imperative      
  BigInteger factorialI(Int n)
  {      
      // Calling Static Method      
      return StaticFiborial.factorialI(n)      
  }      
  // Instance Method - Fibonacci Recursive  
  Int fibonacciR(Int n)  
  {      
      // Calling Static Method      
      return StaticFiborial.fibonacciR(n)  
  }      
  // Instance Method - Factorial Imperative      
  Int fibonacciI(Int n)  
  {      
      // Calling Static Method      
      return StaticFiborial.fibonacciI(n)  
  }      
}    

// Console Program  
public class FiborialApp    
{    
  public static Void main()    
  {
    echo("\nStatic Class")      
    // Calling Static Class and Methods  
    // No instantiation needed. Calling method directly from the class      
    echo("FacImp(5) = ${StaticFiborial.factorialI(5)}")  
    echo("FacRec(5) = ${StaticFiborial.factorialR(5)}")     
    echo("FibImp(11)= ${StaticFiborial.fibonacciI(11)}")      
    echo("FibRec(11)= ${StaticFiborial.fibonacciR(11)}")  
      
    echo("\nInstance Class")      
    // Calling Instance Class and Methods       
    // Need to instantiate before using. Calling method from instantiated object      
    InstanceFiborial ff := InstanceFiborial.make()  
    echo("FacImp(5) = ${ff.factorialI(5)}")  
    echo("FacRec(5) = ${ff.factorialR(5)}")  
    echo("FibImp(11)= ${ff.fibonacciI(11)}")  
    echo("FibRec(11)= ${ff.fibonacciR(11)}")  
      
    // Create a list of integer values to test  
    // From 5 to 50 by 5      
    Int[] values := Int[,]  
    for(i := 5; i <= 50; i += 5)
        values.add(i)
            
    // Benchmarking Fibonacci                           
    // 1 = Factorial Imperative                  
    StaticFiborial.benchmarkAlgorithm(1, values)  
    // 2 = Factorial Recursive      
    StaticFiborial.benchmarkAlgorithm(2, values)  
      
    // Benchmarking Factorial                  
    // 3 = Fibonacci Imperative      
    StaticFiborial.benchmarkAlgorithm(3, values)  
    // 4 = Fibonacci Recursive      
    StaticFiborial.benchmarkAlgorithm(4, values) 
    
    // Stop and exit      
    echo("Press any key to exit...")  
    console := Env.cur  
    userInput := console.in.readLine  
  }
}

And the Output is:




















































Printing the Factorial and Fibonacci Series
using [java] java.math::BigInteger    
using [java] java.lang::StringBuffer  
    
class Fiborial
{    
  // Using a StringBuffer as a list of string elements
  // because of the following compile error: 
  // Ambiguous call append(sys::Str) FiborialSeries.fan ... Fantom Problem
  // I had to use StringBuffer.apend(s, 0, s.length) instead of just StringBuffer.apend(CharSequence s) 
  static Str getFactorialSeries(Int n)    
  {    
    // Create the String that will hold the list    
    StringBuffer series := StringBuffer()  
    // We begin by concatenating the number you want to calculate    
    // in the following format: "!# ="    
    series.append("!", 0, "!".size)  
    series.append(n.toStr, 0, n.toStr.size)  
    series.append(" = ", 0, 3)
    // We iterate backwards through the elements of the series    
    for (i := n; i <= n && i > 0; i--)   
    {
      // and append it to the list    
      series.append(i.toStr, 0, i.toStr.size)
      if (i > 1)  
        series.append(" * ", 0, 3)  
      else     
        series.append(" = ", 0, 3)
    }  
    // Get the result from the Factorial Method    
    // and append it to the end of the list
    Str fac := factorial(n).toStr
    series.append(fac, 0, fac.size)    
    // return the list as a string    
    return series.toStr  
  }    
  
  // Using a StringBuffer as a list of string elements    
  static Str getFibonnaciSeries(Int n)    
  {    
    // Create the String that will hold the list    
    StringBuffer series := StringBuffer()    
    // We begin by concatenating the first 3 values which    
    // are always constant    
    series.append("0, 1, 1", 0, 7)  
    // Then we calculate the Fibonacci of each element    
    // and add append it to the list
    Str fib := ""
    for (i := 2; i <= n; i++)
    {    
      if (i < n)    
        series.append(", ", 0, 2)
      else    
        series.append(" = ", 0, 3)
      
      fib = fibonacci(i).toStr
      series.append(fib, 0, fib.size)  
    }    
    // return the list as a string    
    return series.toStr
  }    
  
  static BigInteger factorial(Int n)    
  {    
    if (n == 1)      
      return BigInteger.ONE
    else      
      return BigInteger.valueOf(n).multiply(factorial(n - 1))  
  }            
  
  static Int fibonacci(Int n)    
  {    
    if (n < 2)
      return 1  
    else      
      return fibonacci(n - 1) + fibonacci(n - 2)  
  }       
}    
  
// Console Program  
public class FiborialSeriesApp    
{    
  public static Void main()    
  {  
    // Printing Factorial Series    
    echo("")  
    echo(Fiborial.getFactorialSeries(5))   
    echo(Fiborial.getFactorialSeries(7)) 
    echo(Fiborial.getFactorialSeries(9)) 
    echo(Fiborial.getFactorialSeries(11)) 
    echo(Fiborial.getFactorialSeries(40))  
    // Printing Fibonacci Series    
    echo("")  
    echo(Fiborial.getFibonnaciSeries(5)) 
    echo(Fiborial.getFibonnaciSeries(7)) 
    echo(Fiborial.getFibonnaciSeries(9)) 
    echo(Fiborial.getFibonnaciSeries(11))  
    echo(Fiborial.getFibonnaciSeries(40)) 
  }
}

And the Output is:


















Mixing Instance and Static Members in the same Class

Instance classes can contain both, instance and static members such as: fields, getters, constructors/initializers, methods, etc.

// Instance Class  
class Fiborial
{  
  // Instance Field  
  private Int instanceCount  
  // Static Field
  // Static field 'staticCount' must be const
  private const static Int staticCount
  // Instance Read-Only Property   
  Int InstanceCount
  {
    get { return &instanceCount }  
  }  
  // Static Fields need to be const. A static const cannot have getter
  // using Static Read-Only Getter instead  
  // As with Static Methods, you cannot reference your class members  
  // with the "this" reference pointer since static members are not  
  // instantiated.  
  /*static Int StaticCount
  {    
    get { return &staticCount }    
  }*/
  static Int getStaticCount() 
  {
    return staticCount
  }
  // Instance Constructor  
  new make() 
  {  
    this.instanceCount = 0  
    echo("\nInstance Constructor ${this.instanceCount}")  
  }  
  // Static Constructor
  // Static constructors are methods executed to initialize the class itself. 
  // They are typically used to initialize static fields.
  static  
  {    
    staticCount = 0    
    echo("\nStatic Constructor $staticCount")
  }      
  // Instance Method  
  Void factorial(Int n) 
  {  
    this.instanceCount += 1  
    echo("\nFactorial($n)")  
  }  
  // Static Method  
  static Void fibonacci(Int n) 
  {  
    // Error: 
    // Cannot set const static field 'staticCount' outside of static initializer 
    // (static constructor) so we cannot increment staticCount
    // staticCount += 1  
    echo("\nFibonacci($n)")  
  }  
}

public class FiborialExtrasApp    
{    
  public static Void main()    
  {  
    // Calling Static Constructor and Methods  
    // No need to instantiate  
    Fiborial.fibonacci(5)  
      
    // Calling Instance Constructor and Methods  
    // Instance required  
    Fiborial fib := Fiborial()  
    fib.factorial(5)  
      
    Fiborial.fibonacci(15)  
    fib.factorial(5)  
      
    // Calling Instance Constructor and Methods  
    // for a second object  
    Fiborial fib2 := Fiborial()
    fib2.factorial(5)
      
    echo("")  
    // Calling Static Property  
    echo("Static Count = ${Fiborial.getStaticCount}")  
    // Calling Instance Property of object 1 and 2  
    echo("Instance 1 Count = ${fib.InstanceCount}")  
    echo("Instance 2 Count = ${fib2.InstanceCount}")   
  }
}

And the Output is:

























Factorial using java.lang.Long/sys::Int, java.lang.Double/sys::Float, java.math.BigInteger


using [java] com.carlosqt.util::Stopwatch
using [java] java.math::BigInteger

public class FiborialTypesApp    
{    
  public static Void main()    
  {     
    Stopwatch timer := Stopwatch()    
    Int facIntResult := 0
    Float facDblResult := 0f    
    BigInteger facBigResult := BigInteger.ZERO 
    
    echo("\nFactorial using Int64")  
    // Benchmark Factorial using Int64    
    for (i := 5; i <= 50; i += 5)    
    {    
      timer.start
      facIntResult = factorialInt64(i)    
      timer.stop    
      echo(" ($i) = ${timer.getElapsed} : $facIntResult")  
    }    
    echo("\nFactorial using Float/Double")
    // Benchmark Factorial using Double    
    for (i := 5; i <= 50; i += 5)    
    {    
      timer.start    
      facDblResult = factorialDouble(i)    
      timer.stop                
      echo(" ($i) = ${timer.getElapsed} : $facDblResult")  
    }    
    echo("\nFactorial using BigInteger")    
    // Benchmark Factorial using BigInteger    
    for (i := 5; i <= 50; i += 5)    
    {    
      timer.start();    
      facBigResult = factorialBigInteger(i);    
      timer.stop();    
      echo(" ($i) = ${timer.getElapsed} : $facBigResult")
    }            
  }  
      
  // Int64 Factorial    
  static Int factorialInt64(Int n)    
  {    
    if (n == 1)    
      return 1
    else    
      return n * factorialInt64(n - 1)  
  }  
    
  // Float Factorial  
  static Float factorialDouble(Int n)    
  {    
    if (n == 1)    
      return 1f
    else    
      return n * factorialDouble(n - 1)  
  }  
    
  // BigInteger Factorial   
  static BigInteger factorialBigInteger(Int n)    
  {    
    if (n == 1)    
      return BigInteger.ONE  
    else    
      return BigInteger.valueOf(n).multiply(factorialBigInteger(n - 1))
  }
}

And the Output is:



No comments:

Post a Comment