Initial data commit

Task/Minkowski-question-mark-function/J/minkowski-question-mark-function-1.j

@@ -0,0 +1,31 @@
+ITERCOUNT=: 52
+
+minkowski=: {{
+  f=. 1|y
+  node=. *i.2 2 NB. node of Stern-Brocot tree
+  B=. ''
+  for. i.ITERCOUNT do.
+    B=. B, b=. f>:%/t=. +/node
+    node=. t (1-b)} node
+  end.
+  (<.y)+B+/ .*2^-1+i.ITERCOUNT
+}}
+
+invmink=: {{
+  f=. 1|y
+  cf=. i.0
+  cur=. 0 NB. 1 if generating "top" side of cf
+  cnt=. 1 NB. proposed continued fraction element
+  for. i.ITERCOUNT do.
+    if. f=<. f do.
+      cf=. cf,%cnt break.
+    end.
+    f=. f*2
+    b=. 1 >`<@.cur f
+    cf=. cf,(-.b)#cnt
+    cnt=. 1+b*cnt
+    cur=. cur=b
+    f=. f-cur
+  end.
+  (+%)/(<.y),cf
+}}

Task/Minkowski-question-mark-function/J/minkowski-question-mark-function-2.j

@@ -0,0 +1,2 @@
+   (minkowski@invmink - invmink@minkowski) (p:%%:)3
+1.10713e_6

Task/Minkowski-question-mark-function/J/minkowski-question-mark-function-3.j

@@ -0,0 +1,6 @@
+    print(
+        "{:19.16f} {:19.16f}".format(
+            minkowski(minkowski_inv(4.04145188432738056)),
+            minkowski_inv(minkowski(4.04145188432738056)),
+        )
+    )