How to Run a Reference Execution

Run applications on Signaloid's C0 Reference cores and trace the distribution behind individual variables in your program.

Signaloid C0 Reference cores perform distribution arithmetic with results on-par with a brute-force Monte Carlo simulation, without you writing the sampling and post-processing yourself. Their defining setting is the Reference Quality Level, the number of times the platform re-executes your code. The default C0Pro-Reference core uses a level of 32. For the microarchitecture details, see the Cores reference.

This page covers how to run applications on a C0 Reference core and how to tell the platform which variables to trace. The mechanics of starting a run are the same as for any other Signaloid core, such as C0Pro-S, C0Pro-S+, or C0Pro-Bypass. Pick the Reference core from the core selector, set command-line arguments and data sources as you would for any other core, then run.

To produce distributional output across the re-executions, the platform accumulates particle values for each variable across runs. You tell it which variables to trace by name, file, and line number of the declaration, since the same variable name can appear in multiple scopes. The traced variables must be of double or float base type, including typedef aliases that resolve to those types. The Variable Viewer, available both in the Code Playground and on each repository's detail page, lists every traced and traceable variable in your source.

Reference runs in the Code Playground

Click Toggle variable viewer () on the editor toolbar to open the Variable Viewer for a Code Playground run. In the panel, click Discover () to populate the list. Each row shows the source file and line number of the declaration. Tick a row to trace that variable on the next reference-core run.

On a core without the Reference microarchitecture, the Variable Viewer offers to switch you to a compatible core in one click. Reset marked variables () clears every selected trace. After you change the source code, the panel surfaces a Code updated banner. Click it to re-run discovery against the new code.

For every selected variable, the platform shows a distributional plot wherever the program prints the value. Figure 1 walks through the basic tracing flow on the default C0Pro-Reference core.

Figure 1. A Code Playground run on the default C0Pro-Reference core: opening the Variable Viewer, discovering variables, ticking R and P from main, and watching the traced values appear underlined in stdout, each linking to its distribution. V was not ticked, so its printed output shows only the particle value.

The platform builds the output distribution from the expressions your program actually prints. Print the variable you want to trace, not an expression that uses it. Take double seconds printed with printf("Milliseconds = %lf\n", seconds * 1000): the platform will not produce a distribution for seconds * 1000, even if seconds is traced. Define and print double milliseconds = seconds * 1000 and trace milliseconds instead.

Custom variable traces

Reference runs can also trace individual array elements and the float or double fields of structs. Add Custom Trace opens the Add Custom Variable Trace dialog, where you enter the element expression along with the file and line of its declaration. See Custom trace expressions for the expression syntax, including array ranges and the accepted forms. To stop tracing a custom expression, untick its row. Figure 2 walks through adding a custom trace and running the program with it active.

Figure 2. A Code Playground run on the default C0Pro-Reference core with a custom trace: clicking Add Custom Trace, entering array[1:2] as the Variable Name with main.c and the declaration line of the double array[3] base variable, then running. The stdout underlines array[1] and array[2]. array[0] was not in the range, so its printed output shows only the particle value.

Reference runs for repositories

Before running a repository on a C0 Reference core, pick the variables to trace. On the connected repository's card, click Discover Variables () to open the dedicated Variable Viewer page for that repository (/repositories/detail). The page works the same way as the Code Playground panel. Click Discover () to populate the list, then pick rows to trace or add custom traces.

Figure 3. A Reference run on the Signaloid-Demo-General-C connected repository: clicking Discover Variables to open the dedicated Variable Viewer page, ticking a and c from main, and running on the default C0Pro-Reference core. stdout underlines a and c. b was not ticked, so its printed output shows only the particle value.

Traced variables in signaloid.yaml

For repository runs, you can declare traces in a signaloid.yaml file at the top level of your repository instead of clicking through the UI, using a TraceVariables list. See The "signaloid.yaml" File for the schema and examples.