__global__ void sumab_kernel(T *__restrict__ u, T *__restrict__ v, T *__restrict__ w, const T *__restrict__ uu, const T *__restrict__ vv, const T *__restrict__ ww, const T *__restrict__ ulag1, const T *__restrict__ ulag2, const T *__restrict__ vlag1, const T *__restrict__ vlag2, const T *__restrict__ wlag1, const T *__restrict__ wlag2, const T ab1, const T ab2, const T ab3, const int nab, const int n)