Hi Christophe, > I use PicoLisp to implement a pedagogical language, directly > embedded in PicoLisp. In an exercise about dices, I noticed a > kind of similarity among the results of my students. > ...
Nice! This sounds really interesting. > Now the question. I found discrepancies between PicoLisp: > ... > -> 934 > And Ersatz > ... > -> 967 Right. In fact, three of the four implementations (pil64, pil32, mini and ersatz) will give different results. Only mini and pil32 behave identically. > Is there a reason for those different behaviours ? > > Last thing (mostly for Jon), I read that the PicoLisp generator is > a 64-bit linear congruential random generator (both pil64 and pil32) > with the multiplier 6364136223846793005. That's correct. All four basically do Seed = Seed * 6364136223846793005 + 1 The differences arise from how the Seed is reduced to a 32-bit number after that. pil64 uses the middle 64 bits of the 128-bit result of the multiplication, while pil32 and mini use the highest 32 bits of the 64-bit result. Ersatz does similar to pil32 (i.e. a 64-bit result), but shifts by 33 (I don't know if there was a special reason). ♪♫ Alex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
