address comment

Author: vtavana

dpnp/backend/extensions/window/bartlett.hpp

@@ -45,8 +45,8 @@ class BartlettFunctor
     {
         const auto i = id.get(0);
 
-        data[i] =
-            T(2) / (N - 1) * ((N - 1) / T(2) - sycl::fabs(i - (N - 1) / T(2)));
+        const T alpha = (N - 1) / T(2);
+        data[i] = T(1) - sycl::fabs(i - alpha) / alpha;
     }
 };
 

dpnp/backend/extensions/window/blackman.hpp

@@ -45,8 +45,9 @@ class BlackmanFunctor
     {
         const auto i = id.get(0);
 
-        data[i] = T(0.42) - T(0.5) * sycl::cospi(T(2) * i / (N - 1)) +
-                  T(0.08) * sycl::cospi(T(4) * i / (N - 1));
+        const T alpha = T(2) * i / (N - 1);
+        data[i] = T(0.42) - T(0.5) * sycl::cospi(alpha) +
+                  T(0.08) * sycl::cospi(T(2) * alpha);
     }
 };