#include <stdio.h>
#include <stdlib.h>

void daxpy_(int *N, double *DA, double DX[], int *INCX, double DY[], int *INCY);

int main(  int argc, char *argv[] )
{ 

//
//   Use BLAS subroutine DAXPY to compute A*X[]+Y[] 
//
   const int dim=10;
   double  a, x[dim], y[dim];  
   int i, n, incx, incy;
      
   for ( i = 0; i < dim; i++ ) {
   	   x[i] = i*2.0;
   	   y[i] = dim-i-1.0;
   }
   
   printf("Vettore X[]:\n");
   for ( i = 0; i < dim; i++ ) {
   	   printf(" %lf",x[i]);
   } printf("\n");
   
   printf("Vettore Y[]:\n");
   for ( i = 0; i < dim; i++ ) {
   	   printf(" %lf",y[i]);
   } printf("\n");
   a = 0.5;
   printf("A = %lf\n\n",a);
   n = dim;
   incx = incy = 1;

   daxpy_(&n, &a, x, &incx, y, &incy);

   printf("Vettore risultato di A*X[]+Y[]:\n");
   for ( i = 0; i < dim; i++ ) {
   	   printf(" %lf",y[i]);
   } printf("\n");

   return(0);
}