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

int main(void) {

  double *b = malloc(2*3 * sizeof(double)),
         sum1 = 0.0, sum2 = 0.0, *p;
  int i, j, k;

  for(i = 0; i < 2*3; i++)         /* Initialization   */
    *(b+i) = (double)(i+1);

  *(b + 3*1+2) += 0.1;             /*  b[1][2] += 0.1; */

  for (i = 0; i < 2; i++)          /* Sum of elements  */
    for (j = 0; j < 3; j++){
      printf("b[%d][%d] = %f\n", i, j, *(b + 3*i+j));  
      sum1 += *(b + 3*i+j);        /* sum1 += b[i][j]; */  
    }

  for(i = 0; i < 2*3; i++){        /* Alt summation    */
    printf("el %d: %f\n", i, *(b+i));
    sum2 += *(b + i);   
  }

  printf("Sum1 = %f, sum2 = %f\n", sum1, sum2);
                /* Sum1 = 21.100000, sum2 = 21.100000  */
  
  return 0;
}