apl: mandelbrot real-axis batched z=z²+c (+9 tests, 296/296)

lib/apl/runtime.sx

@@ -836,6 +836,35 @@
           (apl-eq sum-board (apl-scalar 3))
           (apl-and board (apl-eq sum-board (apl-scalar 4))))))))
 
+(define
+  apl-mandelbrot-step
+  (fn
+    (cs z counts alive iters-left)
+    (if
+      (= iters-left 0)
+      counts
+      (let
+        ((still-alive (apl-and alive (apl-le (apl-mul z z) (apl-scalar 4)))))
+        (let
+          ((new-z (apl-mul still-alive (apl-add (apl-mul z z) cs))))
+          (let
+            ((new-counts (apl-add counts still-alive)))
+            (apl-mandelbrot-step
+              cs
+              new-z
+              new-counts
+              still-alive
+              (- iters-left 1))))))))
+
+(define
+  apl-mandelbrot-1d
+  (fn
+    (cs max-iter)
+    (let
+      ((zero (apl-mul cs (apl-scalar 0)))
+        (ones (apl-add (apl-mul cs (apl-scalar 0)) (apl-scalar 1))))
+      (apl-mandelbrot-step cs zero zero ones max-iter))))
+
 (define
   apl-reduce
   (fn