title: Piecewise function parameters for SED or Bandpass in GalSim
body: <p>Is there a way to pass a piecewise (discontinuous) function for the "spec" parameter of SED or the "throughput" parameter of Bandpass? I tried passing a delta function and a triangular function using numpy, but galsim would not accept either as a valid python function.</p>
  
  <p>I want to try drawing an object at a single wavelength, and thought I should modify the SED or the bandpass to have a value only at a single wavelength. If there are better ways to do this, please let me know!</p>