Math Channels

File → Maths (or F6)

Math channels compute new channel values from existing log data. EmVision uses the same emexpr expression language as Display Studio. Expressions are re-evaluated over the open log when you apply changes in the maths dialog.

Expression language (emexpr)

Full syntax, operators, built-in functions, filters, and examples are documented here:

Math Functions (Display Studio) — expression syntax, math.* / filter.* / calc.* / gen.* libraries, literals (0x, 0b), and stateful evaluation.

That page is written for real-time evaluation on the display (100 Hz continuous or on-event). In EmVision the same expression language is applied offline to logged samples. Prefer the syntax and function reference there; evaluation timing and display-only setup fields (Continuous / On Event, reset events) apply on the vehicle, not when analysing a log.

Using maths in EmVision

  1. Open File → Maths (or press F6).
  2. Organise work into groups and expressions (the shared maths config UI).
  3. Name each expression and write an expression that references log channels by name.
  4. Use enum lookup on status-style inputs to insert a named state’s numeric value into the expression when available.
  5. Math channels can reference other math channels as inputs.
  6. Close the dialog or leave it so changes push to the worker — channels update for plots and the measurements panel.

A warning indicator appears on groups or expressions that fail to compile. Fix the expression text and re-apply.

What you can do

  • Scale, offset, and blend channels
  • Filters and derivatives (via filter.* / related functions — see the syntax reference)
  • Boolean and conditional logic (? :, comparisons)
  • Intermediate values with let
  • Binary and hex integer literals (0b, 0x)

Import and export

Math configuration can be shared between projects using the import/export controls in the maths dialog (formula/function files such as .elform / .elfunc where offered by the UI).

Applying and storage

  • Math results are not written back into the original log file.
  • Definitions live in the client configuration and are available in later sessions; use them with user channels when you need custom channel identity (name, units, colour).
  • Recalculation runs against the currently open reference (and related) log data.