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Thread: Sine function, can't get factorial to work

  1. #1
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    Default Sine function, can't get factorial to work

    I've been having issues with trying to get this program to work. The program's purpose is to compute the sine function without using the Math.sin(). At first I had trouble with the for loop but I finally understood how it worked, so it's not much of an issue anymore. My next problem is trying to get this factorial to work. I've look at tutorials and I think I'm doing the right thing but when I compile I get several errors (stated in code).

    Original Code

    /* This program is suppose to compute the Sine function without using Math.sin */
     
    import java.io.*;
    public class x
    {
    public static void main(String args[]) throws IOException
    {
     
    BufferedReader keybd = new BufferedReader(new InputStreamReader(System.in));
     
    double Rad, Sine;
    int MaxE;
    Sine = 0.0;
     
    System.out.println("Enter Radians: ");
    Rad = Double.parseDouble(keybd.readLine());
     
    for (int a = 1; a <= 11; a++)
    {
    Sine += Math.pow(-1,a)*Math.pow(Rad,2*a+1)/factorial(2*a+1);
    }
     
    System.out.println("The value of Sine is " + Sine);
     
    }
     
    }

    Errors

    x.java:20: cannot find symbol
    symbol  : method factorial(int)
    location: class x
    Sine += Math.pow(-1,a)*Math.pow(Rad,2*a+1)/factorial(2*a+1);
                                               ^
    1 error

    I think I'm on the right track but I'm not sure how to troubleshoot these errors yet since I'm still pretty new. Any help is appreciated!
    Last edited by Actinistia; March 16th, 2011 at 02:56 PM. Reason: I shortened up the code to what I needed help with specifically


  2. #2
    mmm.. coffee JavaPF's Avatar
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    Default Re: Sine function, can't get factorial to work

    Hello Actinistia.

    The issue is that factorial(2 * a + 1) is seen as a method and obviousally there isn't this method within your code.
    factorial isn't even a variable within your code so what are you attempting to do here please?
    Please use [highlight=Java] code [/highlight] tags when posting your code.
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  3. #3
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    Default Re: Sine function, can't get factorial to work

    Quote Originally Posted by JavaPF View Post
    Hello Actinistia.

    The issue is that factorial(2 * a + 1) is seen as a method and obviousally there isn't this method within your code.
    factorial isn't even a variable within your code so what are you attempting to do here please?
    Well, I was looking at some code from a different forum, although I wasn't able to get it to work either, and it seemed to make some sense. I tried to incorporate it within my own code but wasn't able to do it successfully. Here's the code I'm referring to:

    public double sin(int n){
       double sum = 0.0;
       for(int i = 1; i <= n; i++){
    	//if i is even, -1 becomes 1
       //else, -1 stays negative
    	   sum += Math.pow(-1,i)/factorial(2*i+1); 
    	  }
       return sum;
    }
     
    public double factorial(int i){
    	 if(i <= 1) return 1;
    	 double product = 1;
    	 for(int j = i; j > 1; j--) product *= j; 
    	 return product;
    }

    It's probably due to my own inexperience since I've only been working with java for a few weeks or so. I did have the
    public double factorial(int i){
    	 if(i <= 1) return 1;
    	 double product = 1;
    	 for(int j = i; j > 1; j--) product *= j; 
    	 return product;
    }

    in there before but I was getting errors so I just decided to delete it since I didn't know what to do with it.

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    Default Re: Sine function, can't get factorial to work

    just this
    import javax.swing.*;

    class fak {

    public static void main(String[]args) {

    int hasil=1;

    int f=Integer.parseInt(JOptionPane.showInputDialog("Ma sukkan Angka : "));

    for(int i=1;i<=f;i++)

    {

    hasil=hasil*i;

    if(f !=i)

    System.out.print(i+"x");

    else

    System.out.print(i+" = ");

    }

    JOptionPane.showMessageDialog(null,"Hasil dari "+f+"! adalah "+hasil);

    System.exit(0);

    }

    }

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    Super Moderator copeg's Avatar
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    Default Re: Sine function, can't get factorial to work

    Quote Originally Posted by erdy_rezki View Post
    just this
    What is that? And why resurrect a year old post, especially when the contribution is gibberish.

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