[hilbert42]

You're testing my memory now. If I recall correctly, at least complex numbers were in the WATFOR (University of Waterloo) FORTRAN-IV compiler that I used in 1968 on the System/360. (That said, I've always understood it was there from at least FORTRAN II.)

I seem to recall needing 'i' for vector stuff, Maxwell's equations etc. (If I'm wrong it must have been on the VAX FORTRAN-IV several years later.

Correct me if I'm wrong.