title: How to set upper and lower bound on B-Spline result to get a reasonable interpolation
body: <p>I have interpolation function:</p>
  
  <pre><code>from scipy import interpolate
  def f(x):
    x_points = [38508,38510,38512]
    y_points = [0.249267578125,0.181396484375,0.1912841796875]
  
    tck = interpolate.splrep(x_points, y_points,k=2,xb=38508,xe=38512)
    return interpolate.splev(x, tck)
  </code></pre>
  
  <p>when i evaluate <code>f(38503)</code> output is <code>0.75</code> which is nothing like y_points.</p>
  
  <p>Any suggestion on how to decrease this error using this or other interpolation methods? </p>