title: matrix and vector multiplication
body: <p>Suppose we have 3*3 matrix like this:</p>
  
  <pre><code>1 3  4
  2 6 8
  9 0 12
  </code></pre>
  
  <p>And some vector  like this:</p>
  
  <pre><code>1   2   3 
  </code></pre>
  
  <p>My question is: how to implement it so that I could multiply one by another? I have example code:</p>
  
  <pre><code>#include &lt;cstdlib&gt;
  #include &lt;math.h&gt;
  #include &lt;iostream&gt;
  
  using namespace std;
  
  int main(int argc, char *argv[])
  {
      int a[3][3]={{ 2,4,3},{1,5,7},{0,2,3}};
      int b[]={2,5,6};
      int c[3];
  
      for (int i=0;i&lt;3;i++){
           c[i]=0;
      }
  
      for (int i=0;i&lt;3;i++){
          for (int j=0;j&lt;3;j++){
              c[i]+=( a[i][j]*b[j]);
          }
      }
  
      for (int i=0;i&lt;3;i++){
          cout&lt;&lt;a[i]&lt;&lt;"  "&lt;&lt;endl;
      }
  
      system("PAUSE");
      return EXIT_SUCCESS;
  }
  </code></pre>
  
  <p>The result I got is:</p>
  
  <pre><code>0x22ff10
  0x22ff1c
  0x22ff28
  </code></pre>