Mon Mar  2 09:44:34 2020 

findiff_test
  R version 3.4.4 (2018-03-15) 
  findiff applies the finite difference formula to a function.

  findiff(3*x-1, 4, 1 ) =  3 
  findiff(3*x-1, 4, 1.0E-06 ) =  3 
  findiff(sin, pi/4, 1 ) =  0.2699545 
  findiff(sin, pi/4, 0.5 ) =  0.5048857 
  findiff(sin, pi/4, 0.01 ) =  0.7035595 
  findiff(sin, pi/4 ) =  0.7071068 

findiff_test
  Normal end of execution.
Mon Mar  2 09:44:34 2020