27 lines
1.5 KiB
Factor
27 lines
1.5 KiB
Factor
USING: help.syntax help.markup arrays sequences ;
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IN: math.ranges
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ARTICLE: "math.ranges" "Numeric ranges"
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"A " { $emphasis "range" } " is a virtual sequence with real number elements "
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"ranging from " { $emphasis "a" } " to " { $emphasis "b" } " by " { $emphasis "step" } ". Ascending as well as descending ranges are supported."
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$nl
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"The class of ranges:"
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{ $subsection range }
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"Creating ranges with integer end-points. The standard mathematical convention is used, where " { $snippet "(" } " or " { $snippet ")" } " denotes that the end-point itself " { $emphasis "is not" } " part of the range; " { $snippet "[" } " or " { $snippet "]" } " denotes that the end-point " { $emphasis "is" } " part of the range:"
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{ $subsection [a,b] }
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{ $subsection (a,b] }
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{ $subsection [a,b) }
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{ $subsection (a,b) }
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{ $subsection [0,b] }
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{ $subsection [1,b] }
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{ $subsection [0,b) }
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"Creating general ranges:"
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{ $subsection <range> }
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"Ranges are most frequently used with sequence combinators as a means of iterating over integers. For example,"
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{ $code "3 10 [a,b] [ sqrt ] map" }
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"Computing the factorial of 100 with a descending range:"
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{ $code "100 1 [a,b] product" }
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"A range can be converted into a concrete sequence using a word such as " { $link >array } ". In most cases this is unnecessary since ranges implement the sequence protocol already. It is necessary if a mutable sequence is needed, for use with words such as " { $link set-nth } " or " { $link change-each } "." ;
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ABOUT: "math.ranges"
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