so mamy things...

static/coffee/services/rationals.coffee

@@ -0,0 +1,80 @@
+define ["app", "angularAMD", "lodash"], (app, angularAMD, _) ->
+
+    app.service "rationals", () ->
+        service =
+            getNominator: (rat) ->
+                if _.contains(rat, "/")
+                    return Number(rat.substr(0, rat.indexOf("/")))
+                Number(rat)
+
+            getDenominator: (rat) ->
+                if _.contains(rat, "/")
+                    return Number(rat.substr(rat.indexOf("/") + 1))
+                1
+
+            getNomDenom: (rat) ->
+                return [service.getNominator(rat), service.getDenominator(rat)]
+
+            gcd: (a, b) ->
+                if b == 0
+                    return a
+                return service.gcd(b, a % b)
+
+            lcm: (a, b) ->
+                return a * b / service.gcd(a, b)
+
+            changeDenominator: (rat, newDenom) ->
+                [nom, denom] = service.getNomDenom(rat)
+                return service.newRat( nom *  newDenom / denom,  newDenom)
+
+            add: (rat1, rat2) ->
+                [nom, denom] = service.getNomDenom(rat2)
+                [nNom, nDenom] = service.getNomDenom(rat1)
+                gcd = service.gcd(nDenom, denom)
+
+                rNom = nom*nDenom + nNom * denom
+                rDenom = denom * nDenom
+                return service.newRat(rNom/gcd , rDenom/gcd)
+
+            minus: (rat1, rat2) ->
+                return service.add(rat1, service.opposite(rat2))
+
+            reduce: (rat) ->
+                [nom, denom] = service.getNomDenom(rat)
+                gcd = service.gcd(nom, denom)
+                return service.newRat(nom/gcd, denom/gcd)
+
+            opposite: (rat) ->
+                [nom, denom] = service.getNomDenom(rat)
+                return service.newRat(-nom, denom)
+
+
+            sum: (rats...) ->
+                ret = "0/1"
+                for rat in rats
+                    ret = service.add(ret, rat)
+                return service.reduce(ret)
+
+            equal: (rat1, rat2) ->
+                [nom1, denom1] = service.getNomDenom(rat1)
+                [nom2, denom2] = service.getNomDenom(rat2)
+                return nom1 * denom2 == nom2 * denom1
+
+            pp: (x) ->
+                [num, denum] = service.getNomDenom(service.reduce(x))
+                if denum == 1
+                    return num
+                return "#{num}/#{denum}"
+
+
+            newRat: (nom , denom) ->
+                if nom * denom >= 0
+                    return "#{Math.abs(nom)}/#{Math.abs(denom)}"
+                return "#{-Math.abs(nom)}/#{Math.abs(denom)}"
+
+        return service
+
+    app.filter "ratpp", ["rationals", (rationals) ->
+        filter = (n) ->
+            return rationals.pp(n)
+        ]