title: Convert __m128d to double
body: <p>I just try to use SSE extensions, and I started with a simple vector dot multiplication.
  So I wrote the following code:</p>
  
  <pre><code>void SSE_vectormult(double * A, double * B)
  {
      __m128d a;
      __m128d b;
      a = _mm_load_pd(A);
      b = _mm_load_pd(B);
      const int mask = 0xf1;
      __m128d res = _mm_dp_pd(a,b,mask);
      A = res;
  }
  </code></pre>
  
  <p>with <code>A</code> and <code>B</code> vectors of the same length. Now, I have to convert the result in <code>__m128d</code> back into <code>double</code>. Is there a easy way to do this (or a conversion function)?<br>
  Thank you!</p>