Originally Posted by
Norm
The static method main() can NOT access any non-static methods or variables in the class. non-static methods and variables are only accessible to methods in instances of the class.
Solutions:
1) Move the code that access the methods out of main to a method in the class. Have main() create an instance of the class and use the reference to the class to call the method.
2) Make everything static so no instance of the class is required.
Yeah, youre right. I had to make my bisection( ) method an instance of my polynomial class. I stored the evalAt ( ) object results into a variable in which I was able to use as an argument to pass through my bisection method. No changes affected on my array. Since I was able to pass everything correctly, I can focus more on getting the overall Bisection method correctly.
Here is my fully functional program: Do keep in mind that the toString ( ) shows +- or --. Ill work on that later.
import java.util.Scanner;
public class Polynomial {
int [] coefficients = new int[3];
int [] powers = new int[3];
public static void main(String[] args)
{
int c1, c2, c3;
Scanner input = new Scanner(System.in);
/*for(int i = 0; i<coefficents.length-1;i++)
{
}
*/
Polynomial P1 = new Polynomial(4, 5, -3, 3, 1, 0);
Polynomial P2 = new Polynomial(1, 1, -2, 3, 1, 0);
System.out.println("Here is the Polynomial 1: " + P1);
System.out.println("Here is the Polynomial 2: " + P2);
int c = P1.evalAt(5);
int d = P2.evalAt(0);
System.out.println("P1 eval = " + c);
System.out.println("P2 eval = " + d);
System.out.println("Bisection " + P1.bisection(c, d));
System.out.println("================================================");
P1.derivative();
System.out.println("Here is the Derivative for P1: " + P1);
P2.derivative();
System.out.println("Here is the Derivative for P2: " + P2);
}
Polynomial(int a, int b, int c, int x, int y, int z)
{
coefficients[0] = a;
coefficients[1] = b;
coefficients[2] = c;
powers[0] = x;
powers[1] = y;
powers[2] = z;
}
public int evalAt(int x)
{
int sum = 0;
for(int i = coefficients.length-1; i>=0;i--)
{
sum = coefficients[i] + x * sum;
//System.out.print(sum + "\t");
}
return sum;
}
public void derivative() // Evaluates the Derivative
{
for(int i = 0; i<=2;i++)
{
coefficients[i] = powers[i] * coefficients[i];
powers[i]--;
}
}
public double bisection(double a, double b)
{
double tolerance = 0.000001;
double m, ya, yb;
double result = 0;
int i = 0;
double A = a;
double B = b;
while( B-A > tolerance)
{
m = (A+B)/2;
ya = m * m - coefficients[2];
yb = A * A - coefficients[2];
if(ya > 0 && ya < 0 || yb <0 && yb > 0 )
{
B = m;
}
else
{
A = m;
}
System.out.println((A+B)/2);
}
result = (A+B)/2;
return result;
}
public String toString()
{
String s = "";
for(int i=0;i<coefficients.length;i++)
{
if(powers[i]==0)
{
s = s + "+" + coefficients[i];
}
else if(powers[i]>0)
s = s + "+" + (coefficients[i]);
else if(powers[i]<0)
{
s = s + "-" + (-coefficients[i]);
}
if(i == 1)
s = s + "x^" + powers[i];
else if(i > 1)
s = s + "x^" + powers[i];
//else if(i == coefficients.length-1)
else
s = coefficients[i] + "x^" + powers[i];
}
return s;
}
}
----jGRASP exec: java Polynomial
Here is the Polynomial 1: 4x^3+5x^1+-3x^0
Here is the Polynomial 2: 1x^3+1x^1+-2x^0
P1 eval = -46
P2 eval = 1
-10.75
-4.875
-1.9375
-0.46875
0.265625
0.6328125
0.81640625
0.908203125
0.9541015625
0.97705078125
0.988525390625
0.9942626953125
0.99713134765625
0.998565673828125
0.9992828369140625
0.9996414184570312
0.9998207092285156
0.9999103546142578
0.9999551773071289
0.9999775886535645
0.9999887943267822
0.9999943971633911
0.9999971985816956
0.9999985992908478
0.9999992996454239
0.999999649822712
Bisection 0.999999649822712
================================================
Here is the Derivative for P1: 12x^2+5x^0-0x^-1
Here is the Derivative for P2: 3x^2+1x^0-0x^-1
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