Data commit

Task/Minkowski-question-mark-function/Julia/minkowski-question-mark-function.julia

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+function questionmark(x)
+    y, p = fldmod(x, 1)
+    q, d = 1 - p, .5
+    while y + d > y
+        p < q ? (q -= p) : (p -= q; y += d)
+        d /= 2
+    end
+    y
+end
+
+function questionmark_inv(x)
+    y, bits = fldmod(x, 1)
+    lo, hi = [0, 1], [1, 1]
+    while (y + /(lo...)) < (y + /(hi...))
+        bit, bits = fldmod(2bits, 1)
+        bit > 0 ? (lo .+= hi) : (hi .+= lo)
+    end
+    y + /(lo...)
+end
+
+x, y = 0.7182818281828, 0.1213141516171819
+for (a, b) ∈ [
+        (5/3, questionmark((1 + √5)/2)),
+        ((√13-7)/6, questionmark_inv(-5/9)),
+        (x, questionmark_inv(questionmark(x))),
+        (y, questionmark(questionmark_inv(y)))]
+    println(a, a ≈ b ? " ≈ " : " != ", b)
+end