code: def rej(vec, vec_onto):
      
  
      # Imports
      import numpy as np
  
      # Calculate and return.
      rej_vec = vec - proj(vec, vec_onto)
      return rej_vec
docs: Vector rejection.
  
      Calculated by subtracting from `vec` the projection of `vec` onto
      `vec_onto`:
  
      .. math::
  
          \\mathsf{vec} - \\mathrm{proj}\\left(\\mathsf{vec},
          \\ \\mathsf{vec\\_onto}\\right)
  
      Parameters
      ----------
      vec
          length-R |npfloat_| --
          Vector to reject
  
      vec_onto
          length-R |npfloat_| --
          Vector onto which `vec` is to be rejected
  
      Returns
      -------
      rej_vec
          length-R |npfloat_| --
          Rejection of `vec` onto `vec_onto`