How to analyse functions and build a FAST diagram
Short answer: In Function analysis choose Add a function: an active verb and a measurable noun, its class, its "why" function, cost and worth. PVology shows worth ÷ cost and wording checks, and draws the FAST diagram from the why links, with an outline for screen readers and Move up / Move down controls.
Verified for PVology 0.19.0 · updated 2026-10-06
Steps
- Open the study and choose 3. Function analysis.
- Under Add a function enter Verb (for example convey) and Noun (for example water), the Class (basic, secondary, required secondary, unwanted, higher or lower order and others) and Why does it exist? to link it in FAST.
- Enter Cost and Worth if known, or allocate cost items with a share; function cost = sum of each item × its share.
- Choose Add function. If the wording could be clearer (a broad verb, a passive verb or a solution in the noun), PVology shows a Function wording check; your team decides.
- Choose FAST diagram to see the functions left (why) to right (how), with the study scope marked by dashed lines.
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