So let me make a simple proposal: define red = 625nm, so called because light of 625nm is commonly perceived as red. Now, you can store all of the following as exact integers:

- Any binary fraction of an inch down to 1/64inch (1/64in = 635 red)
- Any 1/10 of an inch (1/10in = 4064 red)
- Any multiple of 5um (5um = 8 red)

- 1mil = 40.64 red
- 1pspt = 1/72in ~= 564.44 red
- 1/300in (common print resolution) ~= 135.46 red

Here are some other visible-light inspired fundamental distance units and the common distances they can express exactly as binary fractions:

Color name | Exact definition | Wavelength (approximate) | Exact binary fractions for multiples of |
---|---|---|---|

red | 8192/11162109375m | 733.91nm | 1/64in mil pspt dpi nm |

red | 64/89296875m | 716.71nm | 1/64in mil pspt dpi 25nm |

red | 512/744140625m | 688.04nm | 1/64in mil dpi nm |

red | 4/5953125m | 671.92nm | 1/64in .01in dpi um |

red | 32/49609375m | 645.04nm | 1/64in mil 5nm |

red | 1/1587500m | 629.92nm | 1/64in .01in 5um |

yellow | 256/446484375m | 573.37nm | 1/64in mil pspt dpi 5nm |

green | 2/3571875m | 559.93nm | 1/64in .01in pspt 5um |

green | 2048/3720703125m | 550.43nm | 1/64in mil dpi nm |

green | 16/29765625m | 537.53nm | 1/64in mil dpi 25nm |

green | 128/248046875m | 516.03nm | 1/64in mil nm |

green | 1/1984375m | 503.94nm | 1/64in .01in um |

blue | 1024/2232421875m | 458.69nm | 1/64in mil pspt dpi nm |

violet | 8/17859375m | 447.94nm | 1/64in .01in pspt dpi um |

violet | 64/148828125m | 430.03nm | 1/64in mil dpi 5nm |

violet | 1/2381250m | 419.95nm | 1/64in .01in 5um |

violet | 512/1240234375m | 412.83nm | 1/64in mil nm |

violet | 4/9921875m | 403.15nm | 1/64in mil 25nm |

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colors.py | 2.4kB |

Entry first conceived on 19 February 2014, 21:17 UTC, last modified on 19 February 2014, 22:47 UTC

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