title: Nested bSpline basis on R
body: <p>Im using the bSpline function on R (under the splines2 package) and I'm a little confused on the output. My understanding was that if I made sure the knot sequence was nested, then the columns produced in bSpline should also be nested. However, this is not what the output is giving me.</p>
  
  <p>For example, consider the following code</p>
  
  <pre><code>n=20
  library(splines2)
  x &lt;- runif(n)
  Knots &lt;- c(0.25,0.5,0.75)
  Knots2 &lt;- c(0.125,0.25,0.375,0.5,0.625,0.75,0.875)
  P &lt;- bSpline(x,knots=Knots,Boundary.knots=c(0,1))   
  P2 &lt;- bSpline(x,knots=Knots2,Boundary.knots=c(0,1))     
  </code></pre>
  
  <p>The knots that make up the spline in P are contained in P2 but the output shows that none of the columns of P coincide with that of P2.</p>