brew-calc.el

   1 ;;; brew-calc.el --- calc functions for brewing ber
   2 ;;
   3 ;; Copyright (C) 2009 Erik Hetzner
   4 ;;
   5 ;; Author: Erik Hetzner <ehetzner@gmail.com>
   6 ;;
   7 ;; This file is NOT part of GNU Emacs.
   8 ;;
   9 ;; This program is free software: you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published by
  11 ;; the Free Software Foundation, either version 3 of the License, or
  12 ;; (at your option) any later version.
  13 ;;
  14 ;; This program is distributed in the hope that it will be useful,
  15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;; GNU General Public License for more details.
  18 ;;
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21 ;; calc functions for brewing
  22
  23 (require 'org-cook)
  24
  25 (org-food-alist-append 'math-additional-units
  26                        '((degPlato nil "Degrees Plato")))
  27
  28 (setq math-units-table nil)
  29
  30 (defmath brewNorm (v)
  31   "Get the norm of a value with units."
  32   (math-simplify (math-remove-units v)))
  33
  34 (defmath brew2C (temp)
  35   "Ensure that a temperature is in degC."
  36   (let ((old-units (math-units-in-expr-p temp t)))
  37     (math-simplify
  38      (cond ((not old-units)
  39             (error "Not a temperature."))
  40            ((eq (nth 0 old-units) 'degC)
  41             (math-simplify temp))
  42            ((eq (nth 0 old-units) 'degF)
  43             (math-convert-temperature temp '(var degF var-degF) '(var degC var-degC)))))))
  44
  45 (defmath brew2MG_L (expr)
  46   "Ensure that a mass / vol is in mg / L."
  47   (math-convert-units
  48    expr
  49    '(/ (var mg var-m)
  50        (var L var-L))))
  51
  52 (defmath brew2min (expr)
  53   "Ensure that a time is in minutes."
  54   (math-convert-units expr '(var min var-min)))
  55
  56 ;; From Wikipedia, Plato_scale
  57 (defmath brewSG2P (sg)
  58   "Convert from Specific gravity to Plato, correcting SG vector
  59 if necessary."
  60   (let ((sg1 (brewSGCorr sg)))
  61     (* (+ :"-616.868"
  62           (+ (* :"1111.14" sg1)
  63              (+ (* :"-630.272"
  64                    (^ sg1 2))
  65                 (+ (* :"135.997"
  66                       (^ sg1 3))))))
  67        '(var degPlato var-degPlato))))
  68
  69 ;; From Wikipedia, Plato_scale
  70 (defmath brewP2SG (p)
  71   "Convert Plato (degPlato) to specific gravity (unitless)."
  72   (let ((pn (brewNorm p)))
  73     (math-simplify (/ (- 668
  74                          (nroot (- (^ 668 2)
  75                                    (* 820
  76                                       (+ 463 pn)))
  77                                 2))
  78                       410))))
  79
  80 (defmath brew2P (n)
  81   "Ensure that a value is in degrees Plato (degPlato)."
  82   (if (eq (car (math-units-in-expr-p n t)) 'degPlato)
  83       n
  84     (brewSG2P n)))
  85
  86 (defmath brew2SG (n)
  87   "Ensure that a value is in corrected, unitless, specific
  88 gravity points."
  89   (if (eq (car (math-units-in-expr-p n t)) 'degPlato)
  90       (brewP2SG n)
  91     (brewSGCorr n)))
  92
  93 ;;(defmath brewFpn (x)
  94 ;;  (let ((Pn (brewNorm (brew2P x))))
  95 ;;    (+ :"0.48394"
  96 ;;       (+ (* :"0.0024688" Pn)
  97 ;;          (* :"0.00001561" (^ Pn 2))))))
  98
  99 ;;(defmath brewAW (P n)
 100 ;;  (let ((P1 (brewNorm (brew2P P)))
 101 ;;        (n1 (brewNorm (brew2P n))))
 102 ;;    (* (brewFpn P1)
 103 ;;       (- P1 n1))))
 104
 105 (defmath brewAW2AV (aw ae)
 106   "Convert Alcohol by weight to alcohol by volume."
 107   (* aw (/ (brew2SG ae) :"0.79661")))
 108
 109 (defmath brewAV (oe ae)
 110   "Calculate alc by vol. given original extract and apparent
 111 final extract."
 112   (brewAW2AV
 113    (brewAWFix oe ae) ae))
 114
 115 ;; From George Fix, http://hbd.org/hbd/archive/880.html#880-9, due to
 116 ;; Balling.
 117 (defmath brewRE (oe ae)
 118   "Calculate real extraction, given original extract and apparent
 119 final extract."
 120   (let ((oe1 (brewNorm (brew2P oe)))
 121         (ae1 (brewNorm (brew2P ae))))
 122     (math-simplify
 123      (* (+ (* :"0.1808" oe1)
 124            (* :"0.8192" ae1))
 125         '(var degPlato var-degPlato)))))
 126
 127 (defmath brewAWFix (oe ae)
 128   "Calculate alc. by weight, given original extract and apparent
 129 final extract."
 130   (let* ((oe1 (brewNorm (brew2P oe)))
 131          (ae1 (brewNorm (brew2P ae)))
 132          (re (brewNorm (brewRE oe ae))))
 133     (/ (- oe1 re)
 134        (- :"2.0665"
 135           (* :"0.010665" oe1)))))
 136
 137 (defmath brewCalories (oe ae)
 138   "Calculate cal/L, given original extract and apparent final
 139 extract."
 140   (let* ((fg (brew2SG ae))
 141          (a (brewAWFix oe ae))
 142          (re (brewNorm (brewRE oe ae))))
 143     (* (* (* (+ (* :"6.9" a)
 144                 (* :"4.0" (- re :".1")))
 145              fg)
 146           10)
 147        (/ '(var Kcal var-Kcal)
 148           '(var L var-L)))))
 149
 150 (defmath brewRA (oe ae)
 151   "Calculate approximation to real attenuation."
 152   (let ((re (brewNorm (brewRE oe ae)))
 153         (oe1 (brewNorm (brew2P oe))))
 154     (- 1 (/ re oe1))))
 155
 156 (defmath brewAA (oe ae)
 157   "Calculate approximate attenuation."
 158   (let ((ae1 (brewNorm (brew2P ae)))
 159         (oe1 (brewNorm (brew2P oe))))
 160     (- 1 (/ ae1 oe1))))
 161
 162
 163 ;; Per http://www.csgnetwork.com/h2odenscalc.html and
 164 ;; http://www.earthwardconsulting.com/density.xls
 165 (defmath brewRhoCalc (temp)
 166   "Calculate factor by which water at a given temp differs from
 167 water at ref. temp (~4 degC)"
 168   (let ((tempn (brewNorm (brew2C temp))))
 169     (math-simplify
 170      (- 1 (* (/ (+ tempn :"288.9414")
 171                 (* :"508929.2"
 172                    (+ tempn :"68.12963")))
 173              (^ (- tempn :"3.9863") 2))))))
 174
 175 ;; Follows from above, assuming that beer has the same relationship to
 176 ;; temperature as water does.
 177 (defmath brewSGCorr (sg)
 178   "Ensures that specific gravity is in a corrected, unitless
 179 number, rather than a vector containing measured gravity, temp of
 180 sampled liquid, and calibration temp, e.g. [1.010, 74 degF, 20
 181 degC]"
 182   (if (not (vectorp sg))
 183       sg
 184     (let ((ir (nth 1 sg))
 185           (it (nth 2 sg))
 186           (ct (nth 3 sg)))
 187       (/ (* (brewRhoCalc ct) ir)
 188          (brewRhoCalc it)))))
 189
 190 (defmath brewTinsethBigness (ex)
 191   "Calculate the Tinseth 'bigness' AA utilization factor."
 192   (let ((sg (brew2SG ex)))
 193     (* :"1.65"
 194        (^ :"0.000125"
 195           (- sg 1)))))
 196
 197 (defmath brewTinsethBoilTime (time)
 198   "Calculate the Tinseth 'boil time' AA utilization factor."
 199   (let ((min (brewNorm (brew2min time))))
 200     (/ (- 1 (^ e (* min :"-0.04")))
 201        :"4.15")))
 202
 203 (defmath brewTinsethAAUtil (ex m)
 204   "Calculate the Tinseth AA utilization factor."
 205   (* (brewTinsethBigness ex)
 206      (brewTinsethBoilTime m)))
 207
 208 (defmath brewTinsethIBU (time hop-mass aa boil-size ex)
 209   "Calculate the IBUs given a time, mass of hops, aa of hops,
 210 size of boil, and extract (SG or Plato)."
 211   (* (brewTinsethAAUtil ex time)
 212      (brew2MG_L
 213       (/ (* aa hop-mass) boil-size))))
 214
 215