DZone Snippets: decimal code

Floating point round off

jrobertson (James Robertson) — Sat, 06 Sep 2008 00:26:04 GMT

Source: Ruby: Floating point round off [hans-eric.com]

With a little monkey patching we can add custom round off methods to the Float class.



class Float

  def round_to(x)

    (self * 10**x).round.to_f / 10**x

  end



  def ceil_to(x)

    (self * 10**x).ceil.to_f / 10**x

  end



  def floor_to(x)

    (self * 10**x).floor.to_f / 10**x

  end

end

Example usage:

num = 138.249
num.round_to(2)
# => 138.25

num.floor_to(2)
# => 138.24

num.round_to(-1)
# => 140.0

Decimal to fraction in Ruby

shell (Michelle) — Tue, 06 Mar 2007 15:21:47 GMT

// Adds a 'to_fraction' method to Float. Eg. 0.5.to_fraction => [1,2]



class Float

  def number_decimal_places

    self.to_s.length-2

  end

  

  def to_fraction

    higher = 10**self.number_decimal_places

    lower = self*higher



    gcden = greatest_common_divisor(higher, lower)



    return (lower/gcden).round, (higher/gcden).round

  end

  

private



  def greatest_common_divisor(a, b)

     while a%b != 0

       a,b = b.round,(a%b).round

     end 

     return b

  end

end

bindec.scm

mcandre (Andrew Pennebaker) — Thu, 08 Feb 2007 03:21:50 GMT

// Convert list of 1s and 0s back to base ten number.



; Andrew Pennebaker

; 5 Feb 2007

; License: GPL

; URL: http://snippets.dzone.com/posts/show/3479



(define bin->dec

	(lambda (b)

		(cond

			((integer? b) b)

			((= (length b) 0) 0)

			(else

				(+

					(* (expt 2 (- (length b) 1)) (car b))

					(bin->dec (cdr b)))))))

decbin.scm

mcandre (Andrew Pennebaker) — Thu, 08 Feb 2007 03:18:23 GMT

// Converts a base ten integer to a list of 1s and 0s



; Andrew Pennebaker

; 3 Feb 2007

; License: GPL

; URL: http://snippets.dzone.com/posts/show/3478



(define dec->bin

	(lambda (d)

		(cond

			((< d 1) (list 0))

			((= d 1) (list 1))

			((> d 1) (append

				(dec->bin (floor (/ d 2)))

				(list (if (= (modulo d 2) 0) 0 1)))))))

Convert a decimal value to hex in Python

kodreaming () — Thu, 13 Jul 2006 19:12:37 GMT

// Convert a dec value to hex



hexValue = "%X" % 256

print hexValue  #100

to-octal function

gregg.irwin (Gregg Irwin) — Tue, 10 Jan 2006 05:59:44 GMT



    to-octal: func [

        "Converts an integer to an octal issue!."

        value [integer!] "Value to be converted"

        /width wd

        /local result pad

    ][

        pad: func [val wd] [head insert/dup val #"0" wd - length? val]

        result: copy #   ; empty issue!

        if 0 = value [return pad result any [wd 1]]

        while [0 <> value] [

            insert result value // 8

            value: round/down value / 8

        ]

        pad result any [wd 1]

    ]

from-octal

gregg.irwin (Gregg Irwin) — Tue, 10 Jan 2006 05:58:35 GMT



    from-octal: func [

        "Converts an octal number to a decimal value."

        octal [any-string! integer!]

        /local result len

    ][

        result: 0

        octal: form octal

        repeat i len: length? octal [

            result: add result (to integer! form octal/:i) * (8 ** (len - i))

        ]

        any [attempt [to integer! result] result]

    ]