Re^12: Algorithm for cancelling common factors between two lists of multiplicands

in reply to Re^11: Algorithm for cancelling common factors between two lists of multiplicands
in thread Algorithm for cancelling common factors between two lists of multiplicands

How do I get that output reduced to a real in scientific format?

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Comment on Re^12: Algorithm for cancelling common factors between two lists of multiplicands Download Code

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Re^13: Algorithm for cancelling common factors between two lists of multiplicands by tmoertel (Chaplain) on Aug 09, 2005 at 06:16 UTC
How do I get that output reduced to a real in scientific format? If you want arbitrary precision, the safest bet is to extract the digits yourself: module ScientificFormat (sciformat) where import Ratio -- return prec+1 digits because I don't round sciformat prec r = sign ++ digits ++ "e" ++ show exp where (ds, exp) = tosci (abs numer) (denominator r) 0 numer = numerator r sign = if signum numer < 0 then "-" else "+" digits = show (head ds') ++ "." ++ concatMap show (tail ds') ds' = take (prec+1) (ds ++ repeat 0) tosci 0 _ _ = ([0], 0) tosci numer denom exp = case numer `div` denom of 0 -> tosci (10 * numer) denom (exp-1) x \| x >= 10 -> tosci numer (10denom) (exp+1) _ -> (digits numer denom, exp) digits n d = let (q,r) = n `quotRem` d in q : digits (10r) d [download] And: `module Main (main) where import FishersExactTest import ScientificFormat main = interact $ sciformat 60 . pCutoff . map (map read . words) . li +nes` [download] Example: `[thor@arinmir fishers-exact-test]$ time ./fet < ex1.dat +8.070604647867604097576877675243109941729476950993498765160880e-7030 real 0m0.839s user 0m0.819s sys 0m0.016s` [download] Cheers, Tom Tom Moertel : Blog / Talks / CPAN / LectroTest / PXSL / Coffee / Movie Rating Decoder	[reply] [d/l] [select]

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Re^13: Algorithm for cancelling common factors between two lists of multiplicands
by tmoertel (Chaplain) on Aug 09, 2005 at 06:16 UTC

How do I get that output reduced to a real in scientific format?

module ScientificFormat (sciformat) where

import Ratio

-- return prec+1 digits because I don't round

sciformat prec r =
    sign ++ digits ++ "e" ++ show exp
  where
    (ds, exp) = tosci (abs numer) (denominator r) 0
    numer     = numerator r
    sign      = if signum numer < 0 then "-" else "+"
    digits    = show (head ds') ++ "." ++ concatMap show (tail ds')
    ds'       = take (prec+1) (ds ++ repeat 0)

tosci 0     _     _   = ([0], 0)
tosci numer denom exp =
    case numer `div` denom of
    0           -> tosci (10 * numer) denom (exp-1)
    x | x >= 10 -> tosci numer (10*denom) (exp+1)
    _           -> (digits numer denom, exp)

digits n d =
    let (q,r) = n `quotRem` d in q : digits (10*r) d
[download]

module Main (main) where
import FishersExactTest
import ScientificFormat
main = interact $ sciformat 60 . pCutoff . map (map read . words) . li
+nes
[download]

[thor@arinmir fishers-exact-test]$ time ./fet < ex1.dat
+8.070604647867604097576877675243109941729476950993498765160880e-7030
real    0m0.839s
user    0m0.819s
sys     0m0.016s
[download]

Cheers,
Tom

Tom Moertel : Blog / Talks / CPAN / LectroTest / PXSL / Coffee / Movie Rating Decoder

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