Does Java have a class for complex numbers?

Question

Does Java have a class for complex numbers?

Answer 1

There's an Apache Commons one called Complex. I don't believe the JDK has one.

Answer 2

No, the JDK does not have one but here is an implementation I have written.

Here is the GITHUB project.

/**  * <code>ComplexNumber</code> is a class which implements complex numbers in Java.   * It includes basic operations that can be performed on complex numbers such as,  * addition, subtraction, multiplication, conjugate, modulus and squaring.   * The data type for Complex Numbers.  * <br /><br />  * The features of this library include:<br />  * <ul>  * <li>Arithmetic Operations (addition, subtraction, multiplication, division)</li>  * <li>Complex Specific Operations - Conjugate, Inverse, Absolute/Magnitude, Argument/Phase</li>  * <li>Trigonometric Operations - sin, cos, tan, cot, sec, cosec</li>  * <li>Mathematical Functions - exp</li>  * <li>Complex Parsing of type x+yi</li>  * </ul>  *   * @author      Abdul Fatir  * @version     1.1  *   */ public class ComplexNumber {     /**     * Used in <code>format(int)</code> to format the complex number as x+yi     */     public static final int XY = 0;     /**     * Used in <code>format(int)</code> to format the complex number as R.cis(theta), where theta is arg(z)     */     public static final int RCIS = 1;     /**     * The real, Re(z), part of the <code>ComplexNumber</code>.     */     private double real;     /**     * The imaginary, Im(z), part of the <code>ComplexNumber</code>.     */     private double imaginary;     /**     * Constructs a new <code>ComplexNumber</code> object with both real and imaginary parts 0 (z = 0 + 0i).     */     public ComplexNumber()     {         real = 0.0;         imaginary = 0.0;     }      /**     * Constructs a new <code>ComplexNumber</code> object.     * @param real the real part, Re(z), of the complex number     * @param imaginary the imaginary part, Im(z), of the complex number     */      public ComplexNumber(double real, double imaginary)     {         this.real = real;         this.imaginary = imaginary;     }      /**     * Adds another <code>ComplexNumber</code> to the current complex number.     * @param z the complex number to be added to the current complex number     */      public void add(ComplexNumber z)     {         set(add(this,z));     }      /**     * Subtracts another <code>ComplexNumber</code> from the current complex number.     * @param z the complex number to be subtracted from the current complex number     */      public void subtract(ComplexNumber z)     {         set(subtract(this,z));     }      /**     * Multiplies another <code>ComplexNumber</code> to the current complex number.     * @param z the complex number to be multiplied to the current complex number     */      public void multiply(ComplexNumber z)     {         set(multiply(this,z));     }     /**     * Divides the current <code>ComplexNumber</code> by another <code>ComplexNumber</code>.     * @param z the divisor     */       public void divide(ComplexNumber z)     {         set(divide(this,z));     }     /**     * Sets the value of current complex number to the passed complex number.     * @param z the complex number     */     public void set(ComplexNumber z)     {         this.real = z.real;         this.imaginary = z.imaginary;     }     /**     * Adds two <code>ComplexNumber</code>.     * @param z1 the first <code>ComplexNumber</code>.     * @param z2 the second <code>ComplexNumber</code>.     * @return the resultant <code>ComplexNumber</code> (z1 + z2).     */     public static ComplexNumber add(ComplexNumber z1, ComplexNumber z2)     {         return new ComplexNumber(z1.real + z2.real, z1.imaginary + z2.imaginary);     }      /**     * Subtracts one <code>ComplexNumber</code> from another.     * @param z1 the first <code>ComplexNumber</code>.     * @param z2 the second <code>ComplexNumber</code>.     * @return the resultant <code>ComplexNumber</code> (z1 - z2).     */       public static ComplexNumber subtract(ComplexNumber z1, ComplexNumber z2)     {         return new ComplexNumber(z1.real - z2.real, z1.imaginary - z2.imaginary);     }     /**     * Multiplies one <code>ComplexNumber</code> to another.     * @param z1 the first <code>ComplexNumber</code>.     * @param z2 the second <code>ComplexNumber</code>.     * @return the resultant <code>ComplexNumber</code> (z1 * z2).     */       public static ComplexNumber multiply(ComplexNumber z1, ComplexNumber z2)     {         double _real = z1.real*z2.real - z1.imaginary*z2.imaginary;         double _imaginary = z1.real*z2.imaginary + z1.imaginary*z2.real;         return new ComplexNumber(_real,_imaginary);     }     /**     * Divides one <code>ComplexNumber</code> by another.     * @param z1 the first <code>ComplexNumber</code>.     * @param z2 the second <code>ComplexNumber</code>.     * @return the resultant <code>ComplexNumber</code> (z1 / z2).     */           public static ComplexNumber divide(ComplexNumber z1, ComplexNumber z2)     {         ComplexNumber output = multiply(z1,z2.conjugate());         double div = Math.pow(z2.mod(),2);         return new ComplexNumber(output.real/div,output.imaginary/div);     }      /**     * The complex conjugate of the current complex number.     * @return a <code>ComplexNumber</code> object which is the conjugate of the current complex number     */      public ComplexNumber conjugate()     {         return new ComplexNumber(this.real,-this.imaginary);     }      /**     * The modulus, magnitude or the absolute value of current complex number.     * @return the magnitude or modulus of current complex number     */      public double mod()     {         return Math.sqrt(Math.pow(this.real,2) + Math.pow(this.imaginary,2));     }      /**     * The square of the current complex number.     * @return a <code>ComplexNumber</code> which is the square of the current complex number.     */      public ComplexNumber square()     {         double _real = this.real*this.real - this.imaginary*this.imaginary;         double _imaginary = 2*this.real*this.imaginary;         return new ComplexNumber(_real,_imaginary);     }     /**     * @return the complex number in x + yi format     */     @Override     public String toString()     {         String re = this.real+"";         String im = "";         if(this.imaginary < 0)             im = this.imaginary+"i";         else             im = "+"+this.imaginary+"i";         return re+im;     }     /**     * Calculates the exponential of the <code>ComplexNumber</code>     * @param z The input complex number     * @return a <code>ComplexNumber</code> which is e^(input z)     */     public static ComplexNumber exp(ComplexNumber z)     {         double a = z.real;         double b = z.imaginary;         double r = Math.exp(a);         a = r*Math.cos(b);         b = r*Math.sin(b);         return new ComplexNumber(a,b);     }     /**     * Calculates the <code>ComplexNumber</code> to the passed integer power.     * @param z The input complex number     * @param power The power.     * @return a <code>ComplexNumber</code> which is (z)^power     */     public static ComplexNumber pow(ComplexNumber z, int power)     {         ComplexNumber output = new ComplexNumber(z.getRe(),z.getIm());         for(int i = 1; i < power; i++)         {             double _real = output.real*z.real - output.imaginary*z.imaginary;             double _imaginary = output.real*z.imaginary + output.imaginary*z.real;             output = new ComplexNumber(_real,_imaginary);         }         return output;     }     /**     * Calculates the sine of the <code>ComplexNumber</code>     * @param z the input complex number     * @return a <code>ComplexNumber</code> which is the sine of z.     */     public static ComplexNumber sin(ComplexNumber z)     {         double x = Math.exp(z.imaginary);         double x_inv = 1/x;         double r = Math.sin(z.real) * (x + x_inv)/2;         double i = Math.cos(z.real) * (x - x_inv)/2;         return new ComplexNumber(r,i);     }     /**     * Calculates the cosine of the <code>ComplexNumber</code>     * @param z the input complex number     * @return a <code>ComplexNumber</code> which is the cosine of z.     */     public static ComplexNumber cos(ComplexNumber z)     {         double x = Math.exp(z.imaginary);         double x_inv = 1/x;         double r = Math.cos(z.real) * (x + x_inv)/2;         double i = -Math.sin(z.real) * (x - x_inv)/2;         return new ComplexNumber(r,i);     }     /**     * Calculates the tangent of the <code>ComplexNumber</code>     * @param z the input complex number     * @return a <code>ComplexNumber</code> which is the tangent of z.     */     public static ComplexNumber tan(ComplexNumber z)     {         return divide(sin(z),cos(z));     }     /**     * Calculates the co-tangent of the <code>ComplexNumber</code>     * @param z the input complex number     * @return a <code>ComplexNumber</code> which is the co-tangent of z.     */     public static ComplexNumber cot(ComplexNumber z)     {         return divide(new ComplexNumber(1,0),tan(z));     }     /**     * Calculates the secant of the <code>ComplexNumber</code>     * @param z the input complex number     * @return a <code>ComplexNumber</code> which is the secant of z.     */     public static ComplexNumber sec(ComplexNumber z)     {         return divide(new ComplexNumber(1,0),cos(z));     }     /**     * Calculates the co-secant of the <code>ComplexNumber</code>     * @param z the input complex number     * @return a <code>ComplexNumber</code> which is the co-secant of z.     */     public static ComplexNumber cosec(ComplexNumber z)     {         return divide(new ComplexNumber(1,0),sin(z));     }     /**     * The real part of <code>ComplexNumber</code>     * @return the real part of the complex number     */     public double getRe()     {         return this.real;     }     /**     * The imaginary part of <code>ComplexNumber</code>     * @return the imaginary part of the complex number     */     public double getIm()     {         return this.imaginary;     }     /**     * The argument/phase of the current complex number.     * @return arg(z) - the argument of current complex number     */     public double getArg()     {         return Math.atan2(imaginary,real);     }     /**     * Parses the <code>String</code> as a <code>ComplexNumber</code> of type x+yi.     * @param s the input complex number as string     * @return a <code>ComplexNumber</code> which is represented by the string.     */     public static ComplexNumber parseComplex(String s)     {         s = s.replaceAll(" ","");         ComplexNumber parsed = null;         if(s.contains(String.valueOf("+")) || (s.contains(String.valueOf("-")) && s.lastIndexOf('-') > 0))         {             String re = "";             String im = "";             s = s.replaceAll("i","");             s = s.replaceAll("I","");             if(s.indexOf('+') > 0)             {                 re = s.substring(0,s.indexOf('+'));                 im = s.substring(s.indexOf('+')+1,s.length());                 parsed = new ComplexNumber(Double.parseDouble(re),Double.parseDouble(im));             }             else if(s.lastIndexOf('-') > 0)             {                 re = s.substring(0,s.lastIndexOf('-'));                 im = s.substring(s.lastIndexOf('-')+1,s.length());                 parsed = new ComplexNumber(Double.parseDouble(re),-Double.parseDouble(im));             }         }         else         {             // Pure imaginary number             if(s.endsWith("i") || s.endsWith("I"))             {                 s = s.replaceAll("i","");                 s = s.replaceAll("I","");                 parsed = new ComplexNumber(0, Double.parseDouble(s));             }             // Pure real number             else             {                 parsed = new ComplexNumber(Double.parseDouble(s),0);             }         }         return parsed;     }     /**     * Checks if the passed <code>ComplexNumber</code> is equal to the current.     * @param z the complex number to be checked     * @return true if they are equal, false otherwise     */     @Override     public final boolean equals(Object z)      {         if (!(z instanceof ComplexNumber))             return false;         ComplexNumber a = (ComplexNumber) z;         return (real == a.real) && (imaginary == a.imaginary);     }     /**     * The inverse/reciprocal of the complex number.     * @return the reciprocal of current complex number.     */     public ComplexNumber inverse()     {         return divide(new ComplexNumber(1,0),this);     }     /**     * Formats the Complex number as x+yi or r.cis(theta)     * @param format_id the format ID <code>ComplexNumber.XY</code> or <code>ComplexNumber.RCIS</code>.     * @return a string representation of the complex number     * @throws IllegalArgumentException if the format_id does not match.     */     public String format(int format_id) throws IllegalArgumentException     {         String out = "";         if(format_id == XY)             out = toString();         else if(format_id == RCIS)         {             out = mod()+" cis("+getArg()+")";         }         else         {             throw new IllegalArgumentException("Unknown Complex Number format.");         }         return out;     } }