Formula Tools
Eight tools for understanding, auditing, and stress-testing formulas — from tracing how a number is built to ranking the inputs that move it most. This page explains which tool to reach for, exactly what each one writes to your workbook, and how they work together in a review.
The eight tools
- Trace Precedents — an interactive upstream tree of every cell that feeds the selected cell.
- Trace Dependents — the downstream blast radius: every cell that depends on the selected cell (two-phase discovery).
- Flow Diagram — one formula rendered as a zoomable node graph you can prune, copy, and save.
- TrustLens — a full formula-analysis workbench: explanation, proof/trust, references, diagram, and an optional editor.
- CalcScope — a live, step-by-step calculation tree with a plain-English “why” and write-free what-if sliders.
- Dock CalcScope — the same breakdown as a docked, follow-the-selection cockpit (Explain / Inputs / Impact / Scope / Hidden).
- Classic Pretty Print — a fast, offline, indented and syntax-colored rendering of a long formula.
- Sensitivity — a tornado chart ranking which inputs move a chosen output the most.
Which tool should I use?
| Your question | Reach for |
|---|---|
| What feeds this cell? | Trace Precedents |
| What breaks if I change this cell? (blast radius) | Trace Dependents |
| Show me one formula’s structure visually | Flow Diagram |
| Step through how a number was calculated, with live values and a plain-English reason | CalcScope |
| Keep a breakdown open and follow my selection as I navigate | Dock CalcScope |
| Try different input values without changing the workbook | CalcScope what-if sliders |
| Deeply inspect a formula’s trust/proof and optionally edit it | TrustLens |
| Read a long, nested formula indented and color-coded (offline, no analysis) | Classic Pretty Print |
| Which inputs move this output the most? | Sensitivity |
Safety & write matrix
These tools are analysis surfaces, but several write to the workbook in specific, bounded ways. This is the honest summary; each page documents its own behavior in detail.
| Tool | Data writes | Temporary highlights | Clipboard / file | Undo |
|---|---|---|---|---|
| Trace Precedents / Dependents | None | Source-cell blue + clicked-cell green fills (restored on close) | None | Highlights bypass Excel undo; auto-restored |
| Flow Diagram | None | Same source/target fills | Copy → image to clipboard; Save → PNG/JPEG/BMP file | As above |
| TrustLens | Only if you commit an edit (Ctrl+Enter) | None of its own | Copy/Save diagram image | Edit-commit clears native undo |
| CalcScope | Only via Edit → Apply; what-if sliders write nothing | Source/navigation fills (restored) | Copy as Text / Markdown / RTF / PNG | Edit-commit clears native undo |
| Dock CalcScope | None (no editor in the cockpit) | Navigation fills; Reveal temporarily un-hides a sheet (restored on close) | None | Highlights bypass undo; auto-restored |
| Classic Pretty Print | None (no evaluation) | Source + reference fills (restored) | Copy raw formula text | As above |
| Sensitivity | Temporarily writes input values during the run, then restores them | None | Copy Data → tab-delimited to clipboard | Perturbations bypass undo (events off); restored programmatically |
Two facts that apply across the group
Scope is the active workbook. Cross-sheet references are followed; references to other workbooks appear as non-traversable leaf nodes. (The Trace ribbon tooltips say “across sheets and workbooks” — in practice external-workbook cells are shown but not opened or traversed.)
Committing a formula edit clears Excel’s native undo. The inline editors in TrustLens and CalcScope write through the audit ledger, so Ctrl+Z will not revert a committed edit — nothing is written unless you explicitly commit (Ctrl+Enter / Apply).
How they work together in a review
- Map the structure. Trace Precedents to see what feeds an output; Trace Dependents to see what a change would touch.
- Understand one formula. Open the Flow Diagram for structure, or CalcScope for a step-by-step breakdown with live values and a plain-English explanation. Dock CalcScope keeps that breakdown following your selection as you read the model.
- Inspect trust and (optionally) fix. TrustLens shows the proof/trust verdict for the formula’s chain and lets you edit the formula in place — its Proof view is driven by the same ledger as Proof & Trust.
- Find the levers. Sensitivity ranks which inputs actually move the output, so you know where the model’s risk concentrates.
- Make it provable. Once you trust an input or formula, bind and sign it in Proof & Trust so the result can be re-justified later.
Screenshots of each pane are planned as a future capture pass; this documentation is written from the add-in source and intentionally ships text-first rather than with placeholder images.