[anthk]

Check CORDIC, please.

https://en.wikipedia.org/wiki/CORDIC

Also, on sqrt functions, even a FP-enabled toy EForth under the Subleq VM (just as a toy, again, but it works) provides some sort of fsqrt functions:

    2 f fsqrt f.
    1.414 ok

Under PFE Forth, something 'bigger':

   40 set-precision ok  
   2e0 fsqrt f. 1.4142135623730951454746218587388284504414 ok 

EForth's FP precision it's tiny but good enough for very small microcontrollers. But it wasn't so far from the exponents the 80's engineers worked to create properly usable machinery/hardware and even software.