Compute in Documents

This chapter recalculates one table and executes one source block. It shows when Jan calculates, runs code, publishes results, and changes source text.

Before You Begin

The supplied exercise kit is prepared by Prepare the User Guide Exercises. Open ~/odra-guide/work/projects/forecast-engine/notes/jan-workflows/computation/report.jan. Run M-x jan-computation-status. Continue when table calculation is operational. Source execution also requires an available adapter and admitted execution policy.

Recalculate the Table

Place point in the Total table and run M-x jan-table-recalculate. Jan resolves references, evaluates the dependency graph, and prepares one checked result update. Use M-x jan-table-debug-formula to inspect the formula without changing the document.

jan-table-recalculate-all calculates all admitted tables in dependency order. A cycle, invalid reference, stale revision, or limit failure preserves the previous cells and source. jan-table-plot always supports a bounded text plot; Gnuplot output is optional and reports unavailable when its adapter is absent.

Execute One Source Block

Move to the supplied Racket block and run M-x jan-execute. Review the language, adapter, session, input, result, time, memory, filesystem, process, and network policy before confirmation. Opening, parsing, presenting, saving, exporting, or publishing the document never executes the block.

Accept the operation only when the request matches the supplied safe example. The result is typed before publication. Inspect it with M-x jan-result-inspect; remove only the result with M-x jan-result-remove. A missing adapter or denied authority is a valid unavailable outcome and leaves the source unchanged.

Use jan-execute-subtree, jan-execute-buffer, or jan-execute-batch only after inspecting the larger target set. jan-call invokes one named admitted target. Cancellation and timeouts stop through the process owner and do not turn partial output into an accepted result.

Edit and Extract Source

Run M-x jan-edit-source to edit the block through a focused owner. Return with M-x jan-return-from-source; the checked edit keeps block delimiters and indentation intact.

Inspect named expansion with M-x jan-noweb-inspect. jan-tangle and jan-tangle-file prepare checked output plans. They do not overwrite a resource with a stale expected revision. jan-library-load admits an exact shared-library source; it does not execute it.

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