BLAS 1::nrm2

KokkosBlas::nrm2()

Header File: KokkosBlas1_nrm2.hpp

Usage: nrm = KokkosBlas::nrm2(x); KokkosBlas::nrm2(r,x);

Computes the square root of the sum of all squares of the absolute values of x.

Interface Single Vector Only

template<class VectorX, class VectorY>
InnerProductSpaceTraits<VectorX::non_const_value_type>::mag_type
nrm2 (const VectorX& X);

Parameters:

• VectorX: A rank-1 Kokkos::View

Requirements:

• X.rank == 1

Interface Single and MultiVector

template<class ReturnVector, class VectorX>
void nrm2 (const ReturnVector& R, const VectorX& X);

Parameters:

• ReturnVector: A rank-0 or rank-1 Kokkos::View
• VectorX: A rank-1 or rank-2 Kokkos::View

Requirements:

• X.rank == R.rank + 1
• R.extent(0) == X.extent(1)
• ReturnVector::non_const_value_type == ReturnVector::value_type

Example

#include<Kokkos_Core.hpp>
#include<KokkosBlas1_nrm2.hpp>

int main(int argc, char* argv[]) {
   Kokkos::initialize();

   int N = atoi(argv[1]);

   Kokkos::View<double*> x("X",N);
   Kokkos::deep_copy(x,3.0);

   double x_nrm = KokkosBlas::nrm2(x);

   printf("X_nrm: %lf Expected: %lf Diff: %e\n",x_nrm,1.0*sqrt(N*3.0*3.0),x_nrm-1.0*sqrt(N*3.0*3.0));

   Kokkos::finalize();
}