title: plotting 2 curves; solid lines instead of dotted
body: <p>I would like to plot two functions in a graph. </p>
  
  <pre><code>r &lt;- rnorm(20,0,1)
  z &lt;- c(1,1,1,1,1,-1,-1,-1,1,-1,1,1,1,-1,1,1,-1,-1,1,-1)
  data &lt;- as.data.frame(na.omit(cbind(z, r)))
  series1 &lt;- ts(cumsum(c(1,data[,2]*data[,1])))
  series2 &lt;- ts(cumsum(c(1,data[,2])))
  </code></pre>
  
  <p>The plot of series2 looks like this.
  <img src="https://i.stack.imgur.com/SeimD.png" alt="enter image description here"></p>
  
  <p>Combining the two curves in one graph with </p>
  
  <pre><code>matplot(cbind(series1, series2), xaxt = "n", xlab = "Time", ylab = "Value", col = 1:3, ann = FALSE, type = 'l')
  </code></pre>
  
  <p>gives this:</p>
  
  <p><img src="https://i.stack.imgur.com/Nc9HY.png" alt="enter image description here"></p>
  
  <p>The curve of series2 is now a dotted line. </p>
  
  <p>I have two questions:</p>
  
  <p>1) How can I change the dotted line into a solid line?</p>
  
  <p>2) The titles for the axis are not shown in either of the graphs. How can I fix that?</p>
  
  <p>Thanks in advance.</p>