title: c++ easiest way to multiply multi-dimensional vector by scalar
body: <p>I'm doing montecarlo simulation on <strong>c++</strong>.
  To keep the property of normal distribution which mean is <strong>0</strong>, I want to multiply random vectors by <strong>-1</strong>.</p>
  
  <p>For example, If I have two random numbers <strong>( -1.4, +0.3 )</strong> which were generated by random generator, I want to add <strong>(+1.4, -0.3)</strong> on random numbers. So I can get <strong>(-1.4, 0.3, 1.4, 0.3)</strong> at my random number vectors.</p>
  
  <p>I want to expand this to multi-dimensional vector. Random numbers should be generated by simulation number and period number. So random number vector should be multi-dimensional.</p>
  
  <p>In case of <strong>1-d</strong> case, I know that I can use transform.
  I want to know how to use transform in <strong>2-d</strong> case. if there are any other better way, I want to know also.</p>
  
  <p>Thanks in advance :)</p>