IN:  diff(ln(x), x = 0)

ERROR: sec function is not in shareware and student version. Have you registered ?
OUT: discont
IN:  diff(ln(x), x = 0 + zero)
OUT: inf
IN:  diff(ln(x), x = 0 - zero)
OUT: -inf
IN:  ln'(0 + zero)
OUT: inf
IN:  ln'(0 - zero)
OUT: -inf
