Question: Java Programming package lab6; import java.util.Scanner; public class Lab6 { public static void main(String[] args) { Scanner cin = new Scanner(System.in); int option; do {
Java Programming
package lab6;
import java.util.Scanner;
public class Lab6 {
public static void main(String[] args) {
Scanner cin = new Scanner(System.in);
int option;
do
{
menu();
System.out.print("Select an option -> ");
option = cin.nextInt();
double x;
if(option == 1){
System.out.print("Enter the degree of the polynomial -> ");
int degree = cin.nextInt();
double[] poly = new double [degree + 1];
int i =0;
if (degree < 0)
System.out.print("Error: The degree of the polynomial must be nonnegative.");
else
{
System.out.print("Enter the coefficients -> ");
while(cin.hasNextDouble()){
poly[i] = cin.nextDouble();
i++;
}
}
}
else if(option == 2) {
if (poly.length == 0)
System.out.println("Error: No polynomial has been created.");
else
{
polyToString(poly);
}
}
else if(option == 3) {
if (poly.length == 0)
System.out.println("Error: No polynomial has been created.");
else {
System.out.print("Enter a value at which the polynomial will be evaluated -> ");
x = cin.nextDouble();
polyToString(poly);
polyEval(poly,x);
}
}
} while (option != 0);
}
public static void menu() {
System.out.println("U N I V A R I A T E P O L Y N O M I A L A P P L I C A T I O N");
System.out.println("=================================================================");
System.out.println("Create a Univariate Polynomial............................... [1]");
System.out.println("Display the Polynomial in Standard Form.......................[2]");
System.out.println("Evaluate the Polynomial at a Point............................[3]");
System.out.println("Exit Program..................................................[0]");
System.out.println("=================================================================");
}
public static String polyToString(double[] poly) {
System.out.print("f(x) = ");
String strPoly = "";
if(poly.length == 1)
strPoly = "" + poly[0];
else if (poly.length == 2) {
if (poly[0] == 1) {
strPoly = "x";
if (poly[1] < 0)
strPoly = strPoly + " - " + poly[1] * -1;
else if (poly[1] > 0)
strPoly = strPoly + " + " + poly[1];
}
else if (poly[0] == -1) {
strPoly = "-x";
if (poly[1] < 0)
strPoly = strPoly + " - " + poly[1] * -1;
else if (poly[1] > 0)
strPoly = strPoly + " + " + poly[1];
}
else if (poly[0] == 0) {
strPoly = "";
if (poly[1] < 0)
strPoly = strPoly + " - " + poly[1] * -1;
else if (poly[1] > 0)
strPoly = strPoly + " + " + poly[1];
}
}
else {
strPoly = poly[0] + "x^" + (poly.length - 1);
for(int i = 0; i < poly.length - 2; i++) {
if (poly[i] == 1)
strPoly = strPoly + " + x^" + (poly.length - i);
else if (poly[i] == -1)
strPoly = strPoly + " - x^" + (poly.length - 1);
else if(poly[i] < 0)
strPoly = strPoly + " - " + (poly[i] * -1) + "x^" + (poly.length - i);
else if(poly[i] > 0)
strPoly = strPoly + " - " + poly[i] + "x^" + (poly.length - i);
}
if (poly[poly.length - 2] == 1)
strPoly = strPoly + " + x";
else if (poly[poly.length - 2] == -1)
strPoly = strPoly + " - x";
else if (poly[poly.length - 2] > 0)
strPoly = strPoly + " + " + poly[poly.length - 2] + "x";
else if (poly[poly.length - 2] < 0)
strPoly = strPoly + " - " + (poly[poly.length - 2] * -1) + "x";
if (poly[poly.length - 1] < 0)
strPoly = strPoly + " - " + (poly[poly.length - 1] * -1);
if (poly[poly.length - 1] > 0)
strPoly = strPoly + " + " + (poly[poly.length - 1]);
System.out.print(strPoly);
} return strPoly;
}
public static double polyEval(double[] poly, double x) {
double eval = 0;
for(int i = 0; i < poly.length; i++) {
eval = eval + (poly[i] * Math.pow(x,poly.length - i));
}
return eval;
}
}
Code in the main method won't run because the of the poly array. Not sure what to do to fix it.
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