public Function add(Function f) {
Quadratic q = (Quadratic) f;
for (int x = 0; x < a.length; x++) {
a[x] += q.get()[x];
}
return this;
}
/** Executes the program. */
public static void main(String[] args) {
double a, b, c;
double start;
double end;
int intervals;
double leftRiemannSum, rightRiemannSum, exactIntegral;
int[] space =
new int[2]; // creates an array to store the indices of spaces that appear in the input.
int j = 0;
System.out.println(
"Enter the three coefficients of a quadratic function separated with spaces:");
Scanner keyboard = new Scanner(System.in);
String input1 = keyboard.nextLine();
/* loops through the input to locate spaces and stores their indices */
for (int i = 0; i < input1.length(); i++) {
if (input1.charAt(i) == ' ') {
space[j] = i;
j++;
}
}
/* retrieves the values of coefficients and converts them to doubles */
a = Double.parseDouble(input1.substring(0, space[0]));
b = Double.parseDouble(input1.substring(space[0] + 1, space[1]));
c = Double.parseDouble(input1.substring(space[1] + 1));
do {
System.out.println(
"Enter the start point and end point of the integration separared with a space: ");
String input2 = keyboard.nextLine();
start = Double.parseDouble(input2.substring(0, input2.indexOf(' ')));
end = Double.parseDouble(input2.substring(input2.indexOf(' ') + 1));
} while (end
< start); // asks the user to enter the intervals again if the start point is greater than
// the end point
do {
System.out.println("Enter the number of partitions of the integration: ");
intervals = keyboard.nextInt();
} while (intervals
<= 0); // asks the user to enter the number of partitions again if it is less than or equal
// to 0
// Calculates the integral
Quadratic integral = new Quadratic(a, b, c);
leftRiemannSum = integral.leftRiemannSum(start, end, intervals);
rightRiemannSum = integral.rightRiemannSum(start, end, intervals);
exactIntegral = integral.integrate(start, end);
// Prints the results
System.out.println();
System.out.println("Interval: [" + start + "," + end + "]");
System.out.println("Partitions: " + intervals);
System.out.println("Left Riemann Sum: " + leftRiemannSum);
System.out.println("Right Riemann Sum: " + rightRiemannSum);
System.out.println("Exact Integral: " + exactIntegral);
System.exit(0);
}