Small fixes

Author: kirillgarbar

src/GraphBLAS-sharp.Backend/Common/ClArray.fs

@@ -362,7 +362,7 @@ module ClArray =
 
                 let gid = ndRange.GlobalID0
 
-                if gid < length then
+                if gid < length && not result.Value then
                     let isExist = (%predicate) vector.[gid]
 
                     if isExist then result.Value <- true @>

src/GraphBLAS-sharp.Backend/Common/Sort/Bitonic.fs

@@ -257,6 +257,7 @@ module Bitonic =
                 int (clContext.ClDevice.LocalMemSize)
                 / (sizeof<int> + sizeof<'a>)
             )
+            / 2
 
         let maxThreadsPerBlock =
             min (clContext.ClDevice.MaxWorkGroupSize) (localSize / 2)
@@ -476,4 +477,4 @@ module Bitonic =
 
                 kernelGlobal.KernelFunc ndRangeGlobal rows values values.Length (localSize * 2)
 
-                queue.RunKernel(kernelGlobal)
+                queue.RunKernel(kernelGlobal)