ComplDemo   —   complex arithmetic

1999 ComplDemo was developed as Applet — once a widely used Java standard deployment for web applications but killed long ago by SUN and Oracle and browsers. The WebStart variant complDemo.jnlp brings so many requirements and restrictions at deployment and use. It can hardly be made usable for all and for long time.

Solution: Get frame4j.jar, install it best (with Java8 *)) as installed extension and
  java ComplDemo
If with Java > 8 installed extensions won't work, say
  java -jar C:\util\jdk\jre\lib\ext\frame4j.jar ComplDemojava ComplDemo

ComplDemo allows to "play" with complex arithmetic operations as implemented in Frame4J's package de.frame4j.math by the class Complex.

Hint *): Therefore you have to copy frame4.jar into the lib\ext directory of the JREs and JDKs used. Since 2015 Frame4J requires Java8.