page_title: Digital sundial
section_title: Fractal sundial
hierarchical_section_title: Digital sundial / Technique / Fractal sundial
caption_attribution_description: English: en:Digital sundial in action
context_page_description: A digital sundial is a clock that indicates the current time with numerals formed by the sunlight striking it. Like a classical sundial, the device contains no moving parts. It uses no electricity nor other manufactured sources of energy. The digital display changes as the sun advances in its daily course.
context_section_description: The theoretical basis for the other construction comes from fractal geometry. For the sake of simplicity, we describe a two-dimensional (planar) version. Let Lθ denote a straight line passing through the origin of a Cartesian coordinate system and making angle θ ∈ [0,π) with the x-axis. For any F ⊂ ℝ² define projθ F to be the perpendicular projection of F on the line  Lθ.
caption: This sundial by Digital sundials international uses just two masks and a plexiglas layer.
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