On Sat, May 8, 2010 at 7:24 PM, RichardOnRails
<richarddummymailbox58...@uscomputergurus.com> wrote:
> Hi,
>
> I'm on a mission to show my granddaughter how Pi can be computed. For
> that, I need Sqrt(2) computed accurately, which I've done. But I need
> to display results in 5-digit groups, space separated.
>
> The following aims at displaying the five-or-less decimal components
> of a 12-decimal-digit number (related to sqrt(2) but ignoring scaling
> and precision for the moment).
>
> bd = BigDecimal("0.141421356237")
> group_sz=5
> re_string = "\\.(\\d{1," + group_sz.to_s + "})+"
> r = Regexp.new(re_string)
> m = r.match(bd.to_s)
> (0..3). each do |i|
> puts( "%s => %s; m[%d] => %s" % [r, m, i, m[i]] )
>
> I get (ignoring scaling for the moment):
>
> (?-mix:\.(\d{1,5})+) => .141421356237; m[0] => .141421356237
> (?-mix:\.(\d{1,5})+) => .141421356237; m[1] => 37 # want 14142
> (?-mix:\.(\d{1,5})+) => .141421356237; m[2] => # want 13562
> (?-mix:\.(\d{1,5})+) => .141421356237; m[3] => # want 37
>
> So the extra set of parentheses I added don't capture the way I want
> them to. I can do it using Ruby to generate a bunch of consecutive
> \d{1,5} groups to satisfy my requirement, but some insightful Regexp
> markup is preferable.
>
> Any ideas?
Does this help?
BigDecimal("0.141421356237").to_s.scan(/(\d{1,5}|\.|\E)/).join(" ")
#=> "0 . 14142 13562 37 E 0"
--
Rick DeNatale
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