Java math expression parser that can take complex numbers as a variable?

Question

I am writing a program in Processing that transforms complex numbers. However, I want to have a method of taking an input string and calculating the transformation using a compl

Answer 1

Use Apache Common Math. It is very easy to use.

You can initialize both real+imaginary parts. You can also initialize them from a string. It supports a wide array of operations that you can do with imaginary numbers.

Here is a example of code for doing some common operations:

package complex;
import static java.lang.String.format;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.apache.commons.math3.complex.Complex;
import org.apache.commons.math3.complex.ComplexFormat;
public class Do 
{
    public static void main(String[] args) 
{
     ComplexFormat format = new ComplexFormat();
    Complex lhs = new Complex(1.0, 3.0);
    Complex rhs = new Complex(2.0, 5.0);

    Complex answer = lhs.add(rhs);       // add two complex numbers
    System.out.println("Add : "+ format.format(answer));
    answer = lhs.subtract(rhs);  // subtract two complex numbers
    System.out.println("Subtract : "+ format.format(answer));
    answer = lhs.conjugate();
    System.out.println("Conjgate : "+ format.format(answer));
    double d = lhs.abs();
    System.out.println("Absolute : "+d);
    Complex first  = new Complex(1.0, 3.0);
    Complex second = new Complex(2.0, 5.0);

    answer = first.log();        // natural logarithm.
            System.out.println("Logarithm : "+ format.format(answer));
    answer = first.cos();        // cosine
            System.out.println("Cosine : "+ format.format(answer));
    answer = first.pow(second);  // first raised to the power of second
            System.out.println("Power : "+ format.format(answer));

            Complex z = new Complex(2.0,2.0);
            Complex z1 = z.reciprocal();
            System.out.println("Recipocal : "+ format.format(z1));

            System.out.println("Absoltue of 2+2i is "+z.abs());
            System.out.println("Argument of 2+2i is "+z.getArgument());

    Complex r = new Complex(6.3,9.6);
    String conj = format.format(r.conjugate());
    String reci = format.format(r.reciprocal());

    System.out.println("Conjugate : "+conj+" Recipocal : "+reci);

    //answer = lhs.abs();          // absolute value
    //answer = lhs.conjugate(rhs); // complex conjugate

    //make complex to string

    ComplexFormat format = new ComplexFormat(); // default format
    Complex c = new Complex(1.1111, 2.2222);
    String s = format.format(c); // s contains "1.11 + 2.22i"
    System.out.println(s);

    //make string to complex

    String z = "2.5+3.6i";
    Complex e = format.parse(z);
    System.out.println(e);

}    
}

Another alternative is FrAid, if you want another option.