37 lines
1.3 KiB
Factor
37 lines
1.3 KiB
Factor
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! Copyright (C) 2017 Jon Harper.
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! See http://factorcode.org/license.txt for BSD license.
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USING: help.markup help.syntax kernel math quotations ;
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IN: math.functions.integer-logs
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HELP: integer-log10
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{ $values
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{ "x" "a positive rational number" }
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{ "n" integer }
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}
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{ $description "Outputs the largest integer " { $snippet "n" } " such that " { $snippet "10^n" } " is less than or equal to " { $snippet "x" } "." }
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{ $errors "Throws an error if " { $snippet "x" } " is zero or negative." } ;
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HELP: integer-log2
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{ $values
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{ "x" "a positive rational number" }
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{ "n" integer }
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}
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{ $description "Outputs the largest integer " { $snippet "n" } " such that " { $snippet "2^n" } " is less than or equal to " { $snippet "x" } "." }
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{ $errors "Throws an error if " { $snippet "x" } " is zero or negative." } ;
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ARTICLE: "integer-logs" "Integer logarithms"
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"The " { $vocab-link "math.functions.integer-logs" } " vocabulary provides exact integer logarithms for all rational numbers:"
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{ $subsections integer-log2 integer-log10 }
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{ $examples
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{ $example
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"USING: prettyprint math.functions.integer-logs sequences ;"
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"{"
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" 5 99 100 101 100000000000000000000"
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" 100+1/2 1/100"
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"} [ integer-log10 ] map ."
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"{ 0 1 2 2 20 2 -2 }"
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}
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} ;
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ABOUT: "integer-logs"
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