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Comment by Bootvis | Hacker News Reader

This seems off:

    >> f(x) = x^2 
    >> f''(4)
    0.9995297887

Oh yeah, derivatives of higher order being less accurate is a known problem. I forgot to specify that, thanks!

Maybe best to just disable it for now, I played with e^x as well and the results were off as well.

Ignoring these, I really like Kalk!

Thank you! Yeah, or at least give a warning.

Beautiful Web GUI, beautiful source code, "cargo install kalk_cli" && it works like a charm! Thanks for sharing this.

Thank you so much! This is my first (and only) Rust project so I'm a bit nervous about the code quality.

look into Dual numbers. That way there is no accuracy loss. More generally look into AD (automatic differentiation). thanks me later, cheers

Maybe the derivation could be done by the complex step trick, if programing an AD system is too hard

Note that if f(x) = x^2 then the second derivative f''(x) = 2, so it looks like you're off by a factor of 2 (as well as the accuracy issue).