1 files changed, 116 insertions, 0 deletions
diff --git a/tex/context/base/mkiv/util-rnd.lua b/tex/context/base/mkiv/util-rnd.lua
new file mode 100644
index 000000000..7504965b2
--- /dev/null
+++ b/tex/context/base/mkiv/util-rnd.lua
@@ -0,0 +1,116 @@
+if not modules then modules = { } end modules ['util-rnd'] = {
+    version   = 1.001,
+    comment   = "companion to luat-lib.mkiv",
+    author    = "Tamara, Adriana, Tomáš Hála & Hans Hagen",
+    copyright = "ConTeXt Development Team", -- umbrella
+    license   = "see context related readme files"
+}
+
+-- The rounding code is a variant on Tomáš Hála <tomas.hala@mendelu.cz; mendelu@thala.cz>
+-- code that is used in the statistical module. We use local variables and a tolerant name
+-- resolver that also permits efficient local aliases. With code like this one
+-- really have to make sure that locals are used because changing the rounding
+-- can influence other code.
+
+local floor, ceil, pow = math.floor, math.ceil, math.pow
+local rawget, type = rawget, type
+local gsub, lower = string.gsub, string.lower
+
+local rounding = { }
+
+local methods = {
+    no = function(num)
+        -- no rounding
+        return num
+    end,
+    up = function(num,coef)
+        -- ceiling rounding
+        coef = coef and pow(10,coef) or 1
+        return ceil(num * coef) / coef
+    end,
+    down = function(num,coef)
+        -- floor rounding
+        coef = coef and pow(10,coef) or 1
+        return floor(num * coef) / coef
+    end,
+    halfup = function(num,coef)
+        -- rounds decimal numbers as usual, numbers with 0.5 up, too (e.g. number -0.5 will be rounded to 0)
+        coef = coef and pow(10,coef) or 1
+        return floor(num * coef + 0.5) / coef
+    end,
+    halfdown = function(num,coef)
+        -- rounds decimal numbers as usual, numbers with 0.5 down, too (e.g. number 0.5 will be rounded to 0)
+        coef = coef and pow(10,coef) or 1
+        return ceil(num * coef -0.5) / coef
+    end,
+    halfabsup = function(num,coef)
+        -- rounds deciaml numbers as usual, numbers with 0.5 away from zero, e.g. numbers -0.5 and 0.5 will be rounded to -1 and 1
+        coef = coef and pow(10,coef) or 1
+        return (num >= 0 and floor(num * coef + 0.5) or ceil(num * coef - 0.5)) / coef
+    end,
+    halfabsdown = function(num,coef)
+        -- rounds deciaml numbers as usual, numbers with 0.5 towards zero, e.g. numbers -0.5 and 0.5 will be rounded both to 0
+        coef = coef and pow(10,coef) or 1
+        return (num <  0 and floor(num * coef + 0.5) or ceil(num * coef - 0.5)) / coef
+    end,
+    halfeven = function(num,coef)
+       -- rounds deciaml numbers as usual, numbers with 0.5 to the nearest even, e.g. numbers 1.5 and 2.5 will be rounded both to 2
+        coef = coef and pow(10,coef) or 1
+        num = num*coef
+        return floor(num + (((num - floor(num)) ~= 0.5 and 0.5) or ((floor(num) % 2 == 1) and 1) or 0)) / coef
+    end,
+    halfodd = function(num,coef)
+        -- rounds deciaml numbers as usual, numbers with 0.5 to the nearest odd (e.g. numbers 1.5 and 2.5 will be rounded to 1 and 3
+        coef = coef and pow(10,coef) or 1
+        num = num * coef
+        return floor(num + (((num - floor(num)) ~= 0.5 and 0.5) or ((floor(num) % 2 == 1) and 0) or 1)) / coef
+    end,
+}
+
+methods.default = methods.halfup
+
+rounding.methods = table.setmetatableindex(methods,function(t,k)
+    local s = gsub(lower(k),"[^a-z]","")
+    local v = rawget(t,s)
+    if not v then
+        v = t.halfup
+    end
+    t[k] = v
+    return v
+end)
+
+-- If needed I can make a high performance one.
+
+local defaultmethod = methods.halfup
+
+rounding.round = function(num,dec,mode)
+    if type(dec) == "string" then
+        mode = dec
+        dec  = 1
+    end
+    return (mode and methods[mode] or defaultmethods)(num,dec)
+end
+
+number.rounding = rounding
+
+-- -- Tomáš' test numbers:
+
+-- local list = { 5.49, 5.5, 5.51, 6.49, 6.5, 6.51, 0.5, 12.45 }
+--
+-- for method, round in table.sortedhash(number.rounding.methods) do
+--     for i=1,#list do
+--         local n = list[i]
+--         print(n,method,round(n,k),round(n,k,3))
+--     end
+-- end
+--
+-- local myround = number.rounding.methods["HALF ABS DOWN"]
+--
+-- for i=1,#list do
+--     local n = list[i]
+--     print(n,"Half Abs Down",number.rounding.round(n,1,"Half Abs Down"))
+--     print(n,"HALF_ABS_DOWN",number.rounding.round(n,1,"HALF_ABS_DOWN"))
+--     print(n,"HALF_ABS_DOWN",myround(n,1))
+-- end
+
+return rounding