Fixed PR 7650.  iota now uses (+ start (* n step)) to calculate the elements, instead of successive subtractions.
Fixed PR 7650. 
iota now uses (+ start (* n step)) to calculate the elements, instead of successive subtractions.

svn: r6025

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket