java.math.BigInteger

**r035198x** · Mar 19 '07, 11:55 AM

Originally posted by shana07

I don't understand about this program is doing. Could someone please tell me what it is about. Because I have gcd function in one program that calls this function. Thanks a lot

Code:

 
switch (opcode) {
case GCD: out = b1.gcd(b2).toString();
break;

Code:

/**
* Returns a BigInteger whose value is the greatest common divisor of
* <tt>abs(this)</tt> and <tt>abs(val)</tt>. Returns 0 if
* <tt>this==0 &amp;&amp; val==0</tt>.
*
* @param val value with with the GCD is to be computed.
* @return <tt>GCD(abs(this), abs(val))</tt>
*/
public BigInteger gcd(BigInteger val) {
if (val.signum == 0)
	 return this.abs();
	else if (this.signum == 0)
	 return val.abs();
 
MutableBigInteger a = new MutableBigInteger(this);
MutableBigInteger b = new MutableBigInteger(val);
 
MutableBigInteger result = a.hybridGCD(b);
 
return new BigInteger(result, 1);
}

which part specifically do you not understand?

**shana07** · Mar 19 '07, 12:05 PM

Originally posted by r035198x

which part specifically do you not understand?

The java package code. From my reading, signum is either '+', '-' or 0.
Then, mutableBigInteg er is for what?
As for gcd (a, b) calculation actually is about
a.gcd(b)
Then it involves with operator 'mod' to get remainder.
Where can I check those operators?

Code:

public BigInteger gcd(BigInteger val) {
if (val.signum == 0)
	 return this.abs();
	else if (this.signum == 0)
	 return val.abs();
 
MutableBigInteger a = new MutableBigInteger(this);
MutableBigInteger b = new MutableBigInteger(val);
 
MutableBigInteger result = a.hybridGCD(b);
 
return new BigInteger(result, 1);
}

**r035198x** · Mar 19 '07, 12:12 PM

Originally posted by shana07

The java package code. From my reading, signum is either '+', '-' or 0.
Then, mutableBigInteg er is for what?
As for gcd (a, b) calculation actually is about
a.gcd(b)
Then it involves with operator 'mod' to get remainder.
Where can I check those operators?

Code:

public BigInteger gcd(BigInteger val) {
if (val.signum == 0)
	 return this.abs();
	else if (this.signum == 0)
	 return val.abs();
 
MutableBigInteger a = new MutableBigInteger(this);
MutableBigInteger b = new MutableBigInteger(val);
 
MutableBigInteger result = a.hybridGCD(b);
 
return new BigInteger(result, 1);
}

MutableBigInteg er is another class in the java.math package. It's implementation of hybridGCD is

Code:

 
MutableBigInteger hybridGCD(MutableBigInteger b) {
		// Use Euclid's algorithm until the numbers are approximately the
		// same length, then use the binary GCD algorithm to find the GCD.
		MutableBigInteger a = this;
		MutableBigInteger q = new MutableBigInteger(),
						  r = new MutableBigInteger();
		while (b.intLen != 0) {
			if (Math.abs(a.intLen - b.intLen) < 2)
				return a.binaryGCD(b);
			a.divide(b, q, r);
			MutableBigInteger swapper = a;
			a = b; b = r; r = swapper;
		}
		return a;
	}

**shana07** · Mar 19 '07, 12:27 PM

Originally posted by r035198x

MutableBigInteg er is another class in the java.math package. It's implementation of hybridGCD is

Code:

 
MutableBigInteger hybridGCD(MutableBigInteger b) {
		// Use Euclid's algorithm until the numbers are approximately the
		// same length, then use the binary GCD algorithm to find the GCD.
		MutableBigInteger a = this;
		MutableBigInteger q = new MutableBigInteger(),
						  r = new MutableBigInteger();
		while (b.intLen != 0) {
			if (Math.abs(a.intLen - b.intLen) < 2)
				return a.binaryGCD(b);
			a.divide(b, q, r);
			MutableBigInteger swapper = a;
			a = b; b = r; r = swapper;
		}
		return a;
	}

Oh it's there...alright . TQ
One more question I need to consult you.Is it possible for me to replace any operators inside this class (only gcd subroutines)? Seems I can't do mutation on my program (that calls gcd class) .
* Aim - to do mutation to this gcd function. Because I remember last time, I tried on other java default pakcages and from netbean I can't open that package anymore once I changed it (unzipped the packages and zipped back).....sorry If this confusing you....

**r035198x** · Mar 19 '07, 12:50 PM

Originally posted by shana07

Oh it's there...alright . TQ
One more question I need to consult you.Is it possible for me to replace any operators inside this class (only gcd subroutines)? Seems I can't do mutation on my program (that calls gcd class) .
* Aim - to do mutation to this gcd function. Because I remember last time, I tried on other java default pakcages and from netbean I can't open that package anymore once I changed it (unzipped the packages and zipped back).....sorry If this confusing you....

Do not change any classes in your java directories.
If you need to use any of them, copy them somewhere else and edit them there if you need to.

**shana07** · Mar 20 '07, 03:43 AM

Originally posted by r035198x

Do not change any classes in your java directories.
If you need to use any of them, copy them somewhere else and edit them there if you need to.

Meaning to say that this is possible for me to do so isn't.
I need your advice regarding this please..
1. I have copied those two default java classes in my program under test
2. I renamed classes names as below:

java.math.BigIn teger >>> jonelo.sugar.ma th.MutableBigIn tegerMutant
java.math.Mutab leBigInteger >>> jonelo.sugar.ma th.BigIntMutant

3. And I have renamed all methods/variables/constructors with BigIntMutant
and MutableBigInteg erMutant

4. Is that possible for me to ask my program to refer to these two new classes when it calls gcd (I changed gcd method >>> gcdMutant).

Code:

case GCD:       out = b1.gcdMutant(b2).toString();
                            break;

When I compile my main program - these 3 errors occured, Please advise what should I do..thank you

Main.java:31: cannot find symbol
symbol : class BigIntMutant
location: package jonelo.sugar.ma th
import jonelo.sugar.ma th.BigIntMutant ;
^
Main.java:32: cannot find symbol
symbol : class MutableBigInteg erMutant
location: package jonelo.sugar.ma th
import jonelo.sugar.ma th.MutableBigIn tegerMutant;
^
Main.java:528: cannot find symbol
symbol : method gcdMutant(java. math.BigInteger )
location: class java.math.BigIn teger
case GCD: out = b1.gcdMutant(b2 ).toString();
^
3 errors

**r035198x** · Mar 20 '07, 05:11 AM

Originally posted by shana07

Meaning to say that this is possible for me to do so isn't.
I need your advice regarding this please..
1. I have copied those two default java classes in my program under test
2. I renamed classes names as below:

java.math.BigIn teger >>> jonelo.sugar.ma th.MutableBigIn tegerMutant
java.math.Mutab leBigInteger >>> jonelo.sugar.ma th.BigIntMutant

3. And I have renamed all methods/variables/constructors with BigIntMutant
and MutableBigInteg erMutant

4. Is that possible for me to ask my program to refer to these two new classes when it calls gcd (I changed gcd method >>> gcdMutant).

Code:

case GCD: out = b1.gcdMutant(b2).toString();
break;

When I compile my main program - these 3 errors occured, Please advise what should I do..thank you

Main.java:31: cannot find symbol
symbol : class BigIntMutant
location: package jonelo.sugar.ma th
import jonelo.sugar.ma th.BigIntMutant ;
^
Main.java:32: cannot find symbol
symbol : class MutableBigInteg erMutant
location: package jonelo.sugar.ma th
import jonelo.sugar.ma th.MutableBigIn tegerMutant;
^
Main.java:528: cannot find symbol
symbol : method gcdMutant(java. math.BigInteger )
location: class java.math.BigIn teger
case GCD: out = b1.gcdMutant(b2 ).toString();
^
3 errors

First you will need to make sure that the classes you copied are not referencing other classes that you may not have copied.
Then you need to make sure that your import statements are correct e.g you cannot import a class that you are actually writting code for.

**shana07** · Mar 20 '07, 06:22 AM

Originally posted by r035198x

First you will need to make sure that the classes you copied are not referencing other classes that you may not have copied.
Then you need to make sure that your import statements are correct e.g you cannot import a class that you are actually writting code for.

good example. Help me take a look at this import of the Main class. Why when I compile the Main class comes that errors: can't find class from that import statement....

Code:

package jonelo.bigal;
import java.io.*;
import java.math.BigInteger;
import java.math.BigDecimal;
import jonelo.sugar.math.GeneralMath; // ** Check: This default class from this program

import jonelo.sugar.math.BigIntMutant; //** Check: That's why I put these altered class in here
import jonelo.sugar.math.MutableBigIntegerMutant; //** Check: same as this

**r035198x** · Mar 20 '07, 06:42 AM

Originally posted by shana07

good example. Help me take a look at this import of the Main class. Why when I compile the Main class comes that errors: can't find class from that import statement....

Code:

package jonelo.bigal;
import java.io.*;
import java.math.BigInteger;
import java.math.BigDecimal;
import jonelo.sugar.math.GeneralMath; // ** Check: This default class from this program
 
import jonelo.sugar.math.BigIntMutant; //** Check: That's why I put these altered class in here
import jonelo.sugar.math.MutableBigIntegerMutant; //** Check: same as this

Did you set up the directory structure correctly?

**shana07** · Mar 20 '07, 07:58 AM

Originally posted by r035198x

Did you set up the directory structure correctly?

I think yes, because I just paste the two classes in that directory.
So in the src\jonelo\suga r\math directory contains classes:

GeneralMath
MutableBigInteg erMutant
BigIntMutant

What else should be done you think...

**r035198x** · Mar 20 '07, 08:12 AM

Originally posted by shana07

I think yes, because I just paste the two classes in that directory.
So in the src\jonelo\suga r\math directory contains classes:

GeneralMath
MutableBigInteg erMutant
BigIntMutant

What else should be done you think...

and you put the package name correctly in the classes in the package statement.

**shana07** · Mar 20 '07, 12:09 PM

Originally posted by r035198x

and you put the package name correctly in the classes in the package statement.

Hurm, I need to consult you about this naming directory/package which I am not clear about it. I have located my program such this:

D:\Assignments\ GOOD\BigAl\BigA l\bigal-src\
inside there contains:
jonelo\bigal\ * 3 classes: Main, Algorithm, BigAlException
jonelo\sugar\ma th\ * classes: GeneralMath, BigIntMutant, MutableBigInteg erMutant
jonelo\sugar\ut il\ *1 class: General

So, from where should I put import statement in Main class?
This is my import statements in Main class, please correct if I made wrong

package jonelo.bigal;

import java.io.*;
import java.math.BigIn teger;
import java.math.BigDe cimal;

import jonelo.sugar.ma th.GeneralMath;
import jonelo.sugar.ma th.BigIntMutant ;
import jonelo.sugar.ma th.MutableBigIn tegerMutant;

**r035198x** · Mar 20 '07, 12:58 PM

Originally posted by shana07

Hurm, I need to consult you about this naming directory/package which I am not clear about it. I have located my program such this:

D:\Assignments\ GOOD\BigAl\BigA l\bigal-src\
inside there contains:
jonelo\bigal\ * 3 classes: Main, Algorithm, BigAlException
jonelo\sugar\ma th\ * classes: GeneralMath, BigIntMutant, MutableBigInteg erMutant
jonelo\sugar\ut il\ *1 class: General

So, from where should I put import statement in Main class?
This is my import statements in Main class, please correct if I made wrong

package jonelo.bigal;

import java.io.*;
import java.math.BigIn teger;
import java.math.BigDe cimal;

import jonelo.sugar.ma th.GeneralMath;
import jonelo.sugar.ma th.BigIntMutant ;
import jonelo.sugar.ma th.MutableBigIn tegerMutant;

Why don't you try to put all your classes in one package first.

**shana07** · Mar 21 '07, 10:14 AM

Originally posted by r035198x

Why don't you try to put all your classes in one package first.

This porblem is solved. I created one package like javah/math/BigInteger.
Then I used netbeans to build and run.
About this, i need to ask you: build in netbeans is same as compile?
Then I can see there is one jar created with same program name and build folder?....What happened was, I used prompt before to compile them one by one.

One more thing, what is this statement means?

Code:

 int k = (s1 < s2) ? s1 : s2;

java.math.BigInteger

java.math.BigInteger

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment