Data commit

Task/Nth-root/Bc/nth-root.bc

@@ -0,0 +1,30 @@
+/* Take the nth root of 'a' (a positive real number).
+ * 'n' must be an integer.
+ * Result will have 'd' digits after the decimal point.
+ */
+define r(a, n, d) {
+    auto e, o, x, y, z
+
+    if (n == 0) return(1)
+    if (a == 0) return(0)
+
+    o = scale
+    scale = d
+    e = 1 / 10 ^ d
+
+    if (n < 0) {
+        n = -n
+        a = 1 / a
+    }
+
+    x = 1
+    while (1) {
+        y = ((n - 1) * x + a / x ^ (n - 1)) / n
+        z = x - y
+        if (z < 0) z = -z
+        if (z < e) break
+        x = y
+    }
+    scale = o
+    return(y)
+}