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Encyclopedia > Mixed radix

Mixed radix numeral systems are more general than the usual ones in that the numerical base may vary from position to position. Such numerical representation is advantageous when representing units that are equivalent to each other, but not by the same ratio. For example, 32 weeks, 5 days, 7 hours, 45 minutes, 15 seconds, and 500 milliseconds might be rendered relative to minutes in mixed-radix notation as: A numeral is a symbol or group of symbols that represents a number. ...

 ... 3, 2, 5, 7, 45; 15, 500 , or as ... 10, 10, 7, 24, 60; 60, 1000 310210577244560.15605001000 

In the tabular format, the digits are written above their base, and a semicolon is used to indicate the radix point. In numeral format, each digit has its associated base attached as a subscript, and the radix point's position is indicated by a full stop. In mathematics, radix point refers to the symbol used in numerical representations to separate the integral part of the number (to the left of the radix) from its fractional part (to the right of the radix). ... In mathematics, radix point refers to the symbol used in numerical representations to separate the integral part of the number (to the left of the radix) from its fractional part (to the right of the radix). ... A full stop or period, also called a full point, is the punctuation mark commonly placed at the end of several different types of sentences in English and several other languages. ...


An MRN system can often benefit from a tabular summary. The familiar system for describing the 604800 seconds of a week starting from Sunday Midnight runs as follows:

 Radix: 7 2 12 60 60 Denomination: day half-day hour minute second Place value (seconds): 86400 43200 3600 60 1 Digit translations … day: 0–Sunday 1–Monday 2–Tuesday 3–Wednesday 4–Thursday 5–Friday 6–Saturday half-day: 0–AM 1–PM hour: 0 is written as "12" (!) 

So the MRN 371251251605760 seconds (from Midnight Sunday) is interpreted as 05:51:57 PM Wednesday, 070201202602460 as 12:02:24 AM Sunday. Ad-hoc notations for MRN systems are commonplace.


A second example of a mixed radix numeral system in current use is in the design and use of currency, where a limited set of denominations are minted with the objective of being able to represent any monetary quantity; the amount of money is then represented by the number of coins or banknotes of each denomination. When deciding which denominations to mint (and hence which radices to mix), a compromise is aimed for between a minimal number of different denominations, and a minimal number of individual pieces of coinage required to represent typical quantities. A numeral is a symbol or group of symbols that represents a number. ... This article is about monetary coins. ... A £20 Ulster Bank banknote. ...


An example of a mixed radix numeral system in history is the system of Mayan numerals, which generally used base-20, except for the second place (the "10s" in decimal) which was base-18, so that the first two places counted up to 360 (an approximation to the number of days in the year). A numeral is a symbol or group of symbols that represents a number. ... The Pre-Columbian Maya civilization used a vigesimal (base-20) numeral system. ... Decimal, or less commonly, denary, usually refers to the base 10 numeral system. ...


Mixed-radix numbers of the same base can be manipulated using a generalization of manual arithmetic algorithms. Conversion of values from one mixed base to another is easily accomplished by first converting the place values of the one system into the other, and then applying the digits from the one system against these.


APL includes operators to convert to and from mixed-radix systems. APL (for A Programming Language, or sometimes Array Processing Language) is an array programming language invented in 1962 by Kenneth E. Iverson while at Harvard University. ...


Factorial based radix

Main article: Factoradic The factorial based radix or factoradic is a factorial based mixed radix numeral scheme: radix: 5! 4! 3! 2! 1! decimal: 120 24 6 2 1 In this numbering system, the rightmost digit may be 0 or 1, the next 0, 1, or 2, and so on. ...


An interesting proposal is a factorial based radix, also known as factoradic: In mathematics, the factorial of a natural number n is the product of all positive integers less than and equal to n. ...

 radix: 6 5 4 3 2 1 place value: 5! 4! 3! 2! 1! 0! decimal: 120 24 6 2 1 1 

For example, the biggest number that could be represented with six digits would be 543210 which equals 719 in decimal: 5×5! + 4×4! + 3×3! + 2×2! + 1×1! + 0×1!. It might not be clear at first sight but factorial based numbering system is also unambiguous. No number can be represented by more than one way because the sum of respective factorials multiplied by the index is always the next factorial minus one: Decimal, or less commonly, denary, usually refers to the base 10 numeral system. ...

This can be easily proved with mathematical induction. Mathematical induction is a method of mathematical proof typically used to establish that a given statement is true of all natural numbers, or otherwise is true of all members of an infinite sequence. ...


There is a natural mapping between the integers 0, ..., n! − 1 and permutations of n elements in lexicographic order, when the integers are expressed in factoradic form. In mathematics, especially in abstract algebra and related areas, a permutation is a bijection, from a finite set X onto itself. ...


External resources

Donald E. Knuth. The Art of Computer Programming, Volume 2. pp209 Donald Knuth Donald Ervin Knuth (born January 10, 1938) is a renowned computer scientist and Professor Emeritus at Stanford University. ... Cover of books The Art of Computer Programming is a comprehensive monograph written by Donald Knuth which covers many kinds of programming algorithms and their analysis. ...


External links

  • "Comments on “An Arithmetic Free Parallel Mixed-Radix Conversion Algorithm”". Submitted to IEEE Trans. Circuits and Systems. By Antonio García,Student Member,IEEE, and Graham A. Jullien, Senior Member, IEEE. (PDF) Contains additional references to MRN conversion.

  Results from FactBites:
 
Mixed radix FFT (494 words)
While the technique is useful for splitting the mixed radix FFT into a power-of-2 FFT and one FFT with no power-of-2 computations, it can be used recursively to implement algorithms whose size has an arbitrary number of factors.
The mixed radix FFT is based on the factorization of a size-N FFT into two stages.
In the center branch the mixed radix FFT is used to show how the same factorization technique can be used to implement a large power-of-2 FFT.
Mixed radix: Definition and Links by Encyclopedian.com (214 words)
...Mixed radix Mixed radix Mixed radix numeral systems are unique in that the...can be rendered in mixed-radix notation as: egin{bmatrix} 2, 5, 7, 45, 15, 500...The digits are written above their base, and a semicolon is used to indicate the...
Mixed radix numeral systems are unique in that the numerical base may vary from position to position.
The digits are written above their base, and a semicolon is used to indicate the radix point[?].
  More results at FactBites »


 

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