Testing all prime #'s in an if case until reaching a certain limit.
Hi there,
I've been working on this radical simplifier program that simplifies square roots. There is one point in the program where the code checks to see if the user entered a pure square root that is odd (9,25,49,81 etc), yet in order to properly test it, I need to somehow implement a prime # generator into the if case, and let it test each prime # unitil it gets to some big # like 1,000,000. I have comments at that certain location and have supplied both a prime # checking method and a prime # generating method. I got both methods off some free sample math code websites, and so some of their coding is a little advanced for me. Am I going about this correctly or should I code this another way? Also, any suggestions to improve it would be great. Thanks!
P.S. Hopefully my 4 space indents don't make you crazy. Sorry about that one!
import javax.swing.JOptionPane;
import java.lang.Math;
import java.awt.*;
publicclass squareRoot
{
staticint prime = 5;
staticlong root;
publicstaticvoid main(String[] args)
{
boolean calculating =true;
while (calculating)
{
String entry = JOptionPane.showInputDialog(null,
"Enter a square root to simplify.",
"Square Root Simplifier",
JOptionPane.INFORMATION_MESSAGE);
root = Long.parseLong(entry);
long testPrime = root;
long divisor = 1;
divisor = isPrime(testPrime);
if (divisor == testPrime)
JOptionPane.showMessageDialog(null,
"Your number can't be simplified any further: " + root +" is prime!",
"Square Root Simplifier",
JOptionPane.INFORMATION_MESSAGE);
else
{
if ((root % 2) == 0)//check if it's even
{
if ((Math.sqrt(root) % 2) == 0)//check if it's a pure square root
{
int square = (int)Math.sqrt(root);
JOptionPane.showMessageDialog(null,
"The square root of " + root +" is " + square,
"Square Root Simplifier",
JOptionPane.INFORMATION_MESSAGE);
}
else
{
testPrime = root;
long multiplier = 0;
while (testPrime > 0)
{
testPrime -= 2;
multiplier = testPrime;
multiplier *= multiplier;
if (multiplier < root)
{
if (multiplier == 0)
{
JOptionPane.showMessageDialog(null,
"The square root of " + root +" is already simplified!",
"Square Root Simplifier",
JOptionPane.INFORMATION_MESSAGE);
break;
}
if ((root % multiplier) == 0)
{
testPrime = root / multiplier;
multiplier = (long) Math.sqrt(multiplier);
JOptionPane.showMessageDialog(null,
"The square root of " + root +" simplified is:\n" + multiplier +" times the square root of " + testPrime,
"Square Root Simplifier",
JOptionPane.INFORMATION_MESSAGE);
break;
}
}
}
}
//calculating = false;
}
else//check if it's odd
{
while (prime <= 99999)
{
if ((Math.sqrt(root) % 3 == 0) ||//check if it's a pure square root
(Math.sqrt(root) % 5 == 0) ||
(Math.sqrt(root) % 7 == 0) ||
(Math.sqrt(root) % 11 == 0) ||
(Math.sqrt(root) % 13 == 0))
{//I notice that it always mods it by
int square = (int)Math.sqrt(root);//a prime #. How could I use
JOptionPane.showMessageDialog(null,//genPrime() to do this part?
"The square root of " + root +" is " + square,//Or is there another better way of testing
"Square Root Simplifier",//the primes?
JOptionPane.INFORMATION_MESSAGE);
break;
}
//prime = genPrime();
}
if (prime >= 99999)
{
testPrime = root;
long multiplier = 0;
while (testPrime > 0)
{
testPrime -= 3;
multiplier = testPrime;
multiplier *= multiplier;
if (multiplier < root)
{
if (multiplier == 0)
{
JOptionPane.showMessageDialog(null,
"The square root of " + root +" is already simplified!",
"Square Root Simplifier",
JOptionPane.INFORMATION_MESSAGE);
break;
}
if ((root % multiplier) == 0)
{
testPrime = root / multiplier;
multiplier = (long) Math.sqrt(multiplier);
if (multiplier == 1)
{
JOptionPane.showMessageDialog(null,
"The square root of " + root +" is already simplified!",
"Square Root Simplifier",
JOptionPane.INFORMATION_MESSAGE);
break;
}
else
{
JOptionPane.showMessageDialog(null,
"The square root of " + root +" simplified is:\n" + multiplier +" times the square root of " + testPrime,
"Square Root Simplifier",
JOptionPane.INFORMATION_MESSAGE);
break;
}
}
}
}
}
//calculating = false;
}
}
}
}
//Prime # determiner by Kevin Gong
publicstaticlong isPrime(long testPrime)
{
long test;
test = 2;// should at least use square root
while ( test < testPrime )
{
if ( testPrime % test == 0 )
return test;
if ( test == 2 )
test++;
else
test += 2;
}
return testPrime;
}
//Prime # generator
publicstaticint genPrime()
{
int [] pArray =newint[1000];//primes to check against
int i, num = 0;//num = number of primes saved
boolean check =true;
pArray[0] = 3;//store initial prime
int index = 0, test1 = 3;//first number to test is 5
while(test1 < (pArray[num] * pArray[num]) && (Math.sqrt(root) % prime == 0))
{
index = 0;
check =true;//reset flags
while(check ==true && index <= num && test1 >= (pArray[index] * pArray[index]))
{if(test1 % pArray[index] == 0)
check =false;
else index++;
}
if(check ==true)//found prime
{
if(num < (pArray.length - 1))
pArray[++num] = test1;//save prime
break;
}
test1 += 2;
//if((test1 - 1) % 100000 == 0)
//System.out.println("");//clear every 100,000
}
return test1;
}
}
