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/**************************************************
Write a program to compute dot-products of vectors.  If
v = [a1,a2,...,am] and w = [b1,b2,...,bm] are two vectors of
dimension m, the dot product of v and w is
a1*b1 + a2*b2 + ... + am*bm.  Your program will get a
dimension m from the user, read in two vectors of length m,
and print out their dot product.
**************************************************/
#include <stdio.h>
#include <stdlib.h>

double* readvec(int m);

int main() {
  // Get dimension m
  int m;
  printf("Enter dimension: ");
  fflush(stdout);
  scanf(" %i", &m);

  // Read vector v
  double* v = readvec(m);

  // Read vector w
  double* w = readvec(m);

  // Compute dot product
  double dp = 0;
  for(int i = 0; i < m; ++i) {
    dp += v[i] * w[i];
  }

  // Print result
  printf("Dot product = %g\n", dp);

  // clean-up
  free(v);
  free(w);

  return 0;
}

// reads in a vector of the given dimension and returns
// a pointer to the newly allocated vector
double* readvec(int m) {
  double* result = calloc(m, sizeof(double));
  scanf(" [");
  for (int i=0; i < m; ++i) {
    scanf(" %lg ,", &result[i]);
  }
  scanf(" ]");
  return result;
}