Associatively parametric 2D CAD and geometry calculator.

Algernon is an associatively parametric 2D geometry calculator and CAD tool for Apple iPad, iPhone, and iPod touch devices.

Points, lines, and circles can be constructed with relationships between them and in terms of variables and mathematical formulae. If any one element or variable changes, the geometry is automatically recalculated.

The geometry can be interrogated, dimensioned, inked, annotated with text, and printed (via AirPrint or e-mail export of PDF).

Aimed primarily at engineers and mathematicians (both practising and studying) It is ideally suited for computing geometrical constructions, designing or checking mechanical details, architectural layouts, etc.

Algernon does not need lots of drawing tools; it just needs one for each kind of element. It can automatically determine what kind of construction to create based upon where the user taps. This keeps the user interface clean, simple, and consistent, without restricting its sophistication. It may seem strange at first to those used to conventional CAD, but we believe it will be found natural after a short time.

The app incorporates help and reference documentation, sample model files, and introductory video demonstration.


  • Point, line, and circle construction elements.
  • Constructions of intersections, bisections, and tangents.
    • Can solve circle tangential to 3 others.
  • Mathematical formulae can be specified as parameters (e.g. position, radius, etc.).
  • Variables can be created.
    • Geometrical elements can be used within formulae.
    • Time can be used to create animations.
  • Constructed geometry can be dimensioned:
    • Linear, including projections.
    • Circle radius and diameter.
    • Angles (radians and degrees).
    • Arc-lengths.
    • Internal and external layout.
  • Ink can be drawn over constructed geometry, for printing/PDF.
  • Annotation text can be added.
  • Drawing styles can be created, giving control of:
    • Construction line colour.
    • Ink pen width and colour.
    • Ink dash style.
    • Text font and size.
    • Dimensioning units.
  • Save, print, and e-mail drawings.

For Apple iPad, iPhone, and iPod touch devices running iOS 12.1 or higher.