I am new to the world of java, and having a hard time creating a way to
input a set of coefficients and having "X" attached to them.
For example if i enter the coefficients 7, -4, 15, -5 I would like an output
answer in the form of " 7x^3 - 4x^2 + 15x -5 = 0. If any one has some
suggestions I would greatly appreciate it.
> I am new to the world of java, and having a hard time
> creating a way to
>
> input a set of coefficients and having "X" attached
> to them.
>
> For example if i enter the coefficients 7, -4, 15, -5
> I would like an output
>
> answer in the form of " 7x^3 - 4x^2 + 15x -5 = 0.
> If any one has some
>
> suggestions I would greatly appreciate it.
My suggestion would be to enter those numbers into a String array. Have a statement that first stores the numbers into a string array and then after they're all entered, depending on how many elements there are, add the right x to the power of.
ie.
say your array has 4 elements (like above)
(array insertion code above)
Find the length of the array. Then write a for loop to go through each element adding an X to everything. Now you can either than write another for loop that says to put an x^3 at the first element based on 4-1, the second element would be x^2 based on 4-2 etc... or you can write it all in the same for loop at the same time. Concatonate the X and a ^ (on every element except the last 2... you don't need to write a ^1 or ^0) to the strings that you input and then just add the approperiate exponent based on the array length - your current element positon - 1.
this is what I have so far.
import java.io.*;
public class Factorial {
//Define the main method
public static void main (String[] args) throws IOException {
// Define maximum array size
final int MAXVAL = 1000;
//Define variables
double degree = 0;// degree of polynomial
int [] number = new int [MAXVAL];//array of x
String str;//Input String
int nvals = 0;
//Create a BufferedReader object
BufferedReader in1 = new BufferedReader(
new InputStreamReader(System.in));
//Ask the user for number of input values
System.out.print("Enter amount of coefficients: ");
degree = Integer.parseInt(in1.readLine());
// Calculate squares
for (int i = 0; i < degree; i++)
{
System.out.print("Enter coefficient value a"+ i +": ");
str = in1.readLine();
nvals = Integer.parseInt(str);
}
System.out.println ("The linear equation is : "+ number [nvals] + Factorial.fact(degree));
}
// Define the square method
public static double fact(double degree) {
double answer = 0;//sum of coefficients
char x = 0;
// Calculate squares
for (int i = 0; i < degree; i++)
if (degree == 0)
answer = (x);
else if (degree <= 1)
answer = (degree*Math.pow(x,1));
else
answer = (degree*Math.pow(x,degree-1));
return answer;
}
}
> this is what I have so far.
>
>
> import java.io.*;
> ublic class Factorial {
>
>//Define the main method
> public static void main (String[] args)
> throws IOException {
>
>// Define maximum array size
>final int MAXVAL = 1000;
>
>//Define variables
> double degree = 0;
> // degree of
> polynomial
> int [] number = new int [MAXVAL];
> //array of x
> String str;
>
> /Input String
>int nvals = 0;
>
>//Create a BufferedReader object
> BufferedReader in1 = new BufferedReader(
> new
> InputStreamReader(System.in));
>
> //Ask the user for number of input values
>
> System.out.print("Enter amount of
> coefficients: ");
> degree =
> Integer.parseInt(in1.readLine());
>
> // Calculate squares
>for (int i = 0; i < degree; i++)
> {
> System.out.print("Enter coefficient
> t value a"+ i +": ");
>str = in1.readLine();
>nvals = Integer.parseInt(str);
>
>}
>
>
>
> System.out.println ("The linear equation is : "+
> number [nvals] + Factorial.fact(degree));
>
>}
>
>// Define the square method
> public static double fact(double degree)
> ) {
>
> double answer = 0;//sum of coefficients
>char x = 0;
>
>// Calculate squares
>for (int i = 0; i < degree; i++)
>
> (degree == 0)
>answer = (x);
>
>else if (degree <= 1)
> answer = (degree*Math.pow(x,1));
>
> else
> answer =
> (degree*Math.pow(x,degree-1));
>
>
>return answer;
>
>}
>
>
>}
Ok from what I'm reading, you're prompting the user for a number from a file to determine the number of elements in the array according to the amount of expressions you want... ie if you want 4 you make the array size 4 and want to enter x^3, x^2, x, ## = 0
in your fact method you have this:
char x = 0
which you don't use and are setting it too null.
and where are you even calling the method fact?
ok here's what I'd do
ignoring the class and what not i'll ust write a quick method...
public static void main(String args[])
{
int i = 0;
int counter = 0;
String fullExpression = "";
String [] theArray;
//prompt the user for a number or use the file reader and obtain the number and store it in i
theArray = new String[i]
for( int j = 0; j <theArray.length; j++)
{
//obtain the first coefficent for the first element
//I left this out but use a JoptionPane window here
if((i - counter) != 2))
{
fullExpression = i + ("x^") + (i - counter - 1);
}
else
{
fullExpression = i + ("x");
}
if((i - counter) == 1))
{
fullExpression = i;
}
theArray[counter] = fullExpression;
}
}
>
And btw that code up there is slightly flawed (brackets and semicolons arn't quite in line...)
actually... if you're reading in numbers, you can keep them in string format and not worry about turning them into integers... that would solve my last line of
fullExpression = i;
Secondly, yeah I know programming practice dictates that you make a second method...
first of all you can't create a method within a method secondly... i'll re-post my method as it is on the previous page (flaws and all) and put it into another method using a call statement
> ok here's what I'd do
> ignoring the class and what not i'll ust write a
> quick method...
public static void main(String args[])
{
processing();
}
public static void processing()
{
int i = 0;
int counter = 0;
String fullExpression = "";
String [] theArray;
//prompt the user for a number or use the file
reader and obtain the number and store it in i
theArray = new String[i]
for( int j = 0; j <theArray.length; j++)
{
//obtain the first coefficent for the first
element
//I left this out but use a JoptionPane
window here
if((i - counter) != 2))
{
fullExpression = i + ("x^") + (i
- counter - 1);
}
else
{
fullExpression = i + ("x");
}
if((i - counter) == 1))
{
fullExpression = i;
theArray[counter] = fullExpression;
Message was edited by:
CrimsonYoshi
Message was edited by:
CrimsonYoshi
Message was edited by:
CrimsonYoshi>
no problem... sorry that some of my answers were partially confusing... I have an assignment myself from university involving arrays and circular linked lists... and it's really tough :P
It's in part distracting me since I have about an hour and a half to finish it before it's due and I know I'm not going to come anywhere close to finishing it!
