====== Flowcharts – Dynamic Variables ======
A dynamic variable is any word that begins and ends with a dollar sign (''$''). You use it in an argument in place of an actual file name. For example, where you would put the file name of an input image, you might put ''$input$'' instead. If you check the box next to an empty argument, the argument's name is filled in, surrounded by $ signs: for example, ''$filename$'' for "filename".

The word "input" is just a word of your choice, to remind you which argument it stands for. For example, when taking the ratio of two images, you might use ''$numerator$'' and ''$denominator$'', or even ''$num$'' and ''$denom$'': anything that reminds you what the variable represents.

===== Filling them in from exec =====
After you attach the job to the "exec" module, left-click exec to set its arguments. Its argument window has one labeled text box for each dynamic variable in the attached job. What to enter there is explained in [[intermediate_level:flowcharts:arguments_for_exec|Arguments for "exec"]].

Dynamic variables also work without a flowchart; see [[basic_level:dynamic_variables|Dynamic Variables]] at the Basic level.