Factorial program

[TimGerber]

Hi guys, i need some help with a project, I need to print a table showing the numbers 1 - 10, thentheir factorials, i also need rthe sum of the numbers and the sum of the factorials:\
Number Factorials
=======================
1 1
2 2
3 6
4 24
5 120
6 720
7 5040
8 40320
9 322880
10 3628800
=========================
55 4037913

Any sugguestions...i can't use recursive either...thanx

[TimGerber]

I've can get the factorials....but i can't sum the coulmns...then i got my self confused....can u guys take a look...maybe tell me where i am goin wrong?
thanx
----------------------------------------------------------

public class Test22
{
  public static void main(String[] args) 
  {
    int prod = 1;
    long limit = 10;        // Calculate factorial of integers up to this value
    long factorial = 1;     // Calculate factorial in this variable
     
      System.out.println( "      " + "Number     Factorial" );      // prints titles for columns
      System.out.println( "     " + "========   ===========" );    // prints underlining of titles

    // Loop from 1 to the value of limit
    for(int i = 1; i <= limit; i++)
    {
      factorial = 1;       // Initialize factorial
      int j =2;
      while(j <= i)
        factorial *= j++;
      
      prod = prod * j;
     
      System.out.println( "       " + i + "            " + factorial);

      prodsum = prodsum + prod;
      rowsum = rowsum + i;
     
    }
      
      System.out.println( "   " + "=========================" ); 
      System.out.println( "      " + rowsum + "            " + prodsum );

  }
}

[TimGerber]

ok i worked out how to use prodsum and so on. but i am confused as to why i am using it? my task is due today but it doesn't matter, i will still get a pass for the work i have already done a a previous task.

Even so...if anyone is goin to reply i would appreicate it as i want to learn why and how prod works...as well as why my loop is wack.
thanx

[cosi]

Hey Tim,

Sorry about the homework. You should generally start the homework earlier! ;-)

I can explain your program though I think that it is a bit convoluted. There is a much cleaner and clearer way to code the factorial program you wrote. How about I explain how this way works and see if you understand. If not, then I can explain for you the previous program.

Ed

[cosi]

So here is my rendition of the factorial progam you had... we can discuss this program by section number as I have labelled in the comments.

/* Section A: Variables Inialization */
int factorialFor_i = 1;
int termSum = 0;
int factorialSum = 0;

System.out.println("Number\tFactorial");

int LIMIT = 10;
/* Loop from i =  1 to LIMIT (10) */
for (int i = 1; i <= LIMIT; i++) {

	/* Section B: Loop */
	
	factorialFor_i *= i; 		// B1: update current factorial number
	
	termSum += i; 			// B2: accumulate the sum for the current term i
	factorialSum += factorialFor_i; // B3: accumulate the sum for factorials
	
	System.out.println(i + "\t" + factorialFor_i);
}

/* Section C: Done Loop */
System.out.println("Totals:");
System.out.println(termSum + "\t" + factorialSum);

[cosi]

So let me start with how this program obtains factorials. Let's focus on Section B1:

Remember that this loop's variable i will obtain values from 1 to 10; so the first time the loop executes i = 1, then i = 2, i = 3, and so on.

First Loop Iteration:
Before Loop:
i = 1
factorialFor_i = 1

During Loop:

factorialFor_i *= i;   // Multiply factorial by i (1)

so 1*1 = 1

Result:
i = 1, factorialFor_i = 1

Second Loop:
Before Loop:
i = 2
factorialFor_i = 1

During Loop:

factorialFor_i *= i;   // Multiply factorial by i (2)

1*2 = 2

Result:
i = 2, factorialFor_i = 2

Third Loop:
Before Loop:
i = 3
factorialFor_i = 2

During Loop:

factorialFor_i *= i;   // Multiply factorial by i (2)

2*3 = 6

Result:
i = 3, factorialFor_i = 6

Simple right? Now termSum and factorialSum work the same way.... just step through the loop and see that the values you get are right where you want them. It would be very useful to step through the code in a debugger (if you have been introduced to debuggers, they make life a bit easier by stepping through your code and showing the values for all the variables just like I did here.

I hope this helps! Let me know if you need any more clarification.

Ed

[mukeshbca2]

public class Test22

{

public static void main(String[] args)

{

int prod = 1;

long limit = 10; // Calculate factorial of integers up to this value

long factorial = 1; // Calculate factorial in this variable

 

System.out.println( " " + "Number Factorial" ); // prints titles for columns

System.out.println( " " + "======== ===========" ); // prints underlining of titles

 

// Loop from 1 to the value of limit

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

{

factorial = 1; // Initialize factorial

int j =2;

while(j <= i)

factorial *= j++;

 

prod = prod * j;

 

System.out.println( " " + i + " " + factorial);

 

prodsum = prodsum + prod;

rowsum = rowsum + i;

 

}

 

System.out.println( " " + "=========================" );

System.out.println( " " + rowsum + " " + prodsum );

 

}

}

[adams161]

this is a little confusing. this thread , except for the last two posts by mukeshbca2 is from 2004. Did you find it in a google search?

Mike

[peter_budo]

@mukeshbca2

• almost 6 years too late
• double posted
• copying code from second post and forgot to ask question

If you have question create new thread as this one is of this moment closed...