With 21.2.1 I get: >> (log #c(0 1) #c(0 -1)) Debugger received error of type: DIVISION-BY-ZERO #<a DIVISION-BY-ZERO 0x7f8925037640> Error flushed. gcl, sbcl and ccl all return #C(-1.0 0.0). other non-lisp software agrees. i haven't yet tried master. -JimC -- James Cloos <cloos at jhcloos.com> OpenPGP: 0x997A9F17ED7DAEA6