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Floating point stack

Whilst every sane Forth has a separate floating-point stack, it is not strictly required; an ANS Forth system could theoretically keep floating-point numbers on the data stack. As an additional difficulty, you don't know how many cells a floating-point number takes. It is reportedly possible to write words in a way that they work also for a unified stack model, but we do not recommend trying it. Instead, just say that your program has an environmental dependency on a separate floating-point stack.

floating-stack       -- n         environment       ``floating-stack''
n is non-zero, showing that Gforth maintains a separate floating-point stack of depth n.
fdrop       r --        float       ``f-drop''

fnip       r1 r2 -- r2        gforth       ``f-nip''

fdup       r -- r r        float       ``f-dupe''

fover       r1 r2 -- r1 r2 r1        float       ``f-over''

ftuck       r1 r2 -- r2 r1 r2        gforth       ``f-tuck''

fswap       r1 r2 -- r2 r1        float       ``f-swap''

fpick       u -- r        gforth       ``fpick''
Actually the stack effect is r0 ... ru u -- r0 ... ru r0 .
frot       r1 r2 r3 -- r2 r3 r1        float       ``f-rote''