June 2018 Update

Task/Multifactorial/Julia/multifactorial.julia

@@ -1,18 +1,14 @@
-function multifact{T<:Integer,U<:Integer}(n::T, k::U)
-    -1<n && 0<k || throw(DomainError())
-    1 < k || return factorial(n)
-    r = one(T)
-    for i in n:-k:2
-        r *= i
-    end
-    return r
+function multifact(n::Integer, k::Integer)
+    n > 0 && k > 0 || throw(DomainError())
+    k > 1 || factorial(n)
+    return prod(n:-k:2)
 end
 
-khi = 5
-nhi = 10
-println("Showing multifactorial for n in [1,", nhi, "] and k in [1,", khi, "].")
+const khi = 5
+const nhi = 10
+println("Showing multifactorial for n in [1, $nhi] and k in [1, $khi].")
 for k = 1:khi
-    a = Int64[multifact(i, k) for i in 1:nhi]
-    lab = "n"*"!"^k
-    println(@sprintf("  %-6s =>  ", lab), a)
+    a = multifact.(1:nhi, k)
+    lab = "n" * "!" ^ k
+    @printf("  %-6s →  %s\n", lab, a)
 end