This page picks up from the minimal Mason file example.

Variables
Variables are useful when multiple devices need to be controlled at the same time, or when a calculation needs to be performed.  You can look over the many example circuits provided when Mason is downloaded.

     <?xml version="1.0"?>                                                               
     <mason>                                                                             
        <freq start="100 MHz" stop="200 MHz" step="5 MHz" />                             
        <output name="sample.out" />                                                     
        <variables>                                                                      
           <z0 value="70.71" />                                                          
           <f_mid value="150 MHz" />                                                     
        </variables>                                                                     
        <model alias="TL">                                                               
           <primitive name="simple_transmission_lines/lossless_transmission_line.xml" /> 
        </model>                                                                         
        <port number="1" node="1" impedance="50" />                                      
        <port number="2" node="2" impedance="100" />                                     
        <TL node_list="1 2" >                                                            
           <z0 value="z0" /> the variable name is independent of the primitive argument  
           <f0 value="f_mid" />                                                          
           <theta value="90 deg" />                                                      
        </TL>                                                                            
        <flag output_data_format="dB" set_width="15" />                                  
     </mason>                                                                            


Calculations
The fundamental difference between a calculation and a variable tag is that calculations can be algebraic expressions but cannot be optimized, and the variable's value can be optimized.  One can optimize a variable which feeds into a calculation. of course.  Another difference is there is one variable block, but can be lots of calculation tags.

     <?xml version="1.0"?>                                                               
     <mason>                                                                             
        <freq start="100 MHz" stop="200 MHz" step="5 MHz" />                             
        <output name="sample.out" />                                                     
        <variables>                                                                      
           <f_mid value="150 MHz" />                                                     
        </variables>                                                                     
        <calculation equation="z0=sqrt(100*50)" />                                       
        <model alias="TL">                                                               
           <primitive name="simple_transmission_lines/lossless_transmission_line.xml" /> 
        </model>                                                                         
        <port number="1" node="1" impedance="50" />                                      
        <port number="2" node="2" impedance="100" />                                     
        <TL node_list="1 2" >                                                            
           <z0 value="z0" /> the variable name is independent of the primitive argument  
           <f0 value="f_mid" />                                                          
           <theta value="90 deg" />                                                      
        </TL>                                                                            
        <flag output_data_format="dB" set_width="15" />                                  
     </mason>