title: Attempt to apply non-function in a sequence
body: <p>I'm trying to make a sequence with these conditions:</p>
  
  <pre><code>y&lt;-seq(from=a-2(b-a), to=a+2(b-a), by=4(b-a)/99, length.out=100)
  </code></pre>
  
  <p>Given:</p>
  
  <pre><code>sample=rnorm(50, mean=0, sd=1)
  sample_min=min(sample)
  a&lt;-sample_min
  sample_max=max(sample)
  b&lt;-sample_max
  </code></pre>
  
  <p>And I get the error "attempt to apply non-function in a sequence." How do I fix this?</p>