added support for openArray's for gcd and lcm (#12621)

lib/pure/math.nim

@@ -1062,6 +1062,19 @@ proc gcd*(x, y: SomeInteger): SomeInteger =
     x -= y
   y shl shift
 
+proc gcd*[T](x: openArray[T]): T {.since: (1, 1).} =
+  ## Computes the greatest common (positive) divisor of the elements of ``x``.
+  ##
+  ## See also:
+  ## * `gcd proc <#gcd,T,T>`_ for integer version
+  runnableExamples:
+    doAssert gcd(@[13.5, 9.0]) == 4.5
+  result = x[0]
+  var i = 1
+  while i < x.len:
+    result = gcd(result, x[i])
+    inc(i)
+
 proc lcm*[T](x, y: T): T =
   ## Computes the least common multiple of ``x`` and ``y``.
   ##
@@ -1072,7 +1085,18 @@ proc lcm*[T](x, y: T): T =
     doAssert lcm(13, 39) == 39
   x div gcd(x, y) * y
 
-
+proc lcm*[T](x: openArray[T]): T {.since: (1, 1).} =
+  ## Computes the least common multiple of the elements of ``x``.
+  ##
+  ## See also:
+  ## * `gcd proc <#gcd,T,T>`_ for integer version
+  runnableExamples:
+    doAssert lcm(@[24, 30]) == 120
+  result = x[0]
+  var i = 1
+  while i < x.len:
+    result = lcm(result, x[i])
+    inc(i)
 
 when isMainModule and not defined(JS) and not windowsCC89:
   # Check for no side effect annotation