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$Complex ON/OFF  i/j


EES provides an option in the Complex tab of the Preferences dialog to enable or disable complex algebra.  This directive provides a means of setting the option for complex numbers in the Equations Window.  The directive also optionally allows whether i or j is to be used to represent the square root of -1.  To allow complex algebra with j as the square root of -1, enter


$Complex On j


To disable it, enter


$Complex Off


The complex mode can also be turned on or off by clicking in the Complex pane in the status bar at the bottom of the Equations window.


The $Complex On directive can be used in Subprograms.  It is possible to have the main program operate without complex numbers and call a Subprogram that does the complex calculations.  Note that he real and imaginary parts of a complex number must be passed to the Subprogram separately.  The real part is identified with _r at the end of the variable name.  The imaginary part has a _i at the end of its variable name.  


Modules and functions cannot be used in a program that uses complex calculations.