title: Swift float multiplication error
body: <p>This code fails:</p>
  
  <pre><code>let element: Float = self.getElement(row: 1, column: j)
  let multiplier = powf(-1, j+2)*element
  </code></pre>
  
  <p>with this error:</p>
  
  <blockquote>
    <p>Playground execution failed: :140:51: error: cannot invoke '*' with an argument list of type '(Float, Float)'
                        let multiplier = powf(-1, j+2)*element</p>
  </blockquote>
  
  <p>Bear in mind that this occurs in this block:</p>
  
  <pre><code>for j in 0...self.columnCount {
  </code></pre>
  
  <p>where <code>columnCount</code> is a Float. Also, the first line does execute and so the <code>getElement</code> method indeed returns a Float.</p>
  
  <p>I am completely puzzled by this as I see no reason why it shouldn't work.</p>