title: Matrix multiplication with an array of matrices
body: <p>I have an array of matrices, <code>Z1</code>, and a matrix, <code>Z2</code>. <code>Z1</code>, has dimension <code>[25,2,4]</code> and <code>Z2</code> has dimension <code>[2,10]</code>. </p>
  
  <p>I would like to perform <code>Z1[,,i]%*%Z2</code> for <code>i = 1,2,3,4</code>. Is this possible using sweep of apply? </p>
  
  <p>I can do this using a for loop and do not want to do that here. </p>
  
  <p>An example of the proposed data: <code>Z1 = array(1:200, dim = c(25,2,4));
  Z2 = array(1:20, dim = c(2,10))</code></p>