Perfect Ruler

A type of Ruler considered by Guy (1994) which has distinct marks spaced such that the distances between markscan be used to measure all the distances 1, 2, 3, 4, ... up to some maximum distance . Such a ruler can beconstructed from a Perfect Difference Set by subtracting one from each element. For example, the PerfectDifference Set gives 0, 1, 4, 6, which can be used to measure , , , ,, (so we get 6 distances with only four marks).

References

Guy, R. K. ``Modular Difference Sets and Error Correcting Codes.'' §C10 in Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, pp. 118-121, 1994.

• Sphere
• Sphere-Cylinder Intersection
• Sphere Embedding
• Sphere Eversion
• Sphere Geodesic
• Sphere Packing
• Sphere Point Picking
• Sphere-Sphere Intersection
• Sphere with Tunnel
• Spherical Bessel Differential Equation
• Spherical Bessel Function
• Spherical Bessel Function of the First Kind
• Spherical Bessel Function of the Second Kind
• Spherical Bessel Function of the Third Kind
• Spherical Cap
• Spherical Coordinates
• Spherical Design
• Spherical Excess
• Spherical Frustum
• Spherical Geometry
• Spherical Hankel Function of the First Kind
• Spherical Hankel Function of the Second Kind
• Spherical Harmonic
• Spherical Harmonic Addition Theorem
• Spherical Harmonic Closure Relations