**UNIX**
----
<code fortran>
fortest.f

PROGRAM fortest

! simple program which creates 2 vectors and adds them in a 
! cuda function

IMPLICIT NONE

integer*4 :: i
integer*4, parameter :: N=8
real*4, Dimension(N) :: a, b

DO i=1,N
  a(i)=i*1.0
  b(i)=2.0
END DO

 print *, 'a = ', (a(i), i=1,N)

  CALL kernel_wrapper(a, b, N)

 print *, 'a + 2 = ', (a(i), i=1,N)

END PROGRAM 
</code>


<code c>
cudatest.cu

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cuda.h>
#include <cuda_runtime.h>


// simple kernel function that adds two vectors
__global__ void vect_add(float *a, float *b, int N)
{
   int idx = threadIdx.x;
   if (idx&ltN) a[idx] = a[idx] + b[idx];
}

// function called from main fortran program
extern "C" void kernel_wrapper_(float *a, float *b, int *Np)
{
   float  *a_d, *b_d;  // declare GPU vector copies
   
   int blocks = 1;     // uses 1 block of
   int N = *Np;        // N threads on GPU

   // Allocate memory on GPU
   cudaMalloc( (void **)&a_d, sizeof(float) * N );
   cudaMalloc( (void **)&b_d, sizeof(float) * N );

   // copy vectors from CPU to GPU
   cudaMemcpy( a_d, a, sizeof(float) * N, cudaMemcpyHostToDevice );
   cudaMemcpy( b_d, b, sizeof(float) * N, cudaMemcpyHostToDevice );

   // call function on GPU
   vect_add<<< blocks, N >>>( a_d, b_d, N);

   // copy vectors back from GPU to CPU
   cudaMemcpy( a, a_d, sizeof(float) * N, cudaMemcpyDeviceToHost );
   cudaMemcpy( b, b_d, sizeof(float) * N, cudaMemcpyDeviceToHost );

   // free GPU memory
   cudaFree(a_d);
   cudaFree(a_d);
   return;
}
</code>




Makefile


Test: fortest.f cudatest.o
        gfortran -L /usr/local/cuda/lib -I /usr/local/cuda/include -lcudart 
		         -lcuda fortest.f cudatest.o
cudatest.o: cudatest.cu 
        nvcc -c -O3 cudatest.cu
clean:
        rm a.out cudatest.o cudatest.linkinfo