Bah! I'm an idiot. If I use f64, I get: ln(e^iπ) = 0+3.141592653589793i ln(-1) = 0+3.141592653589793i
On 3/9/21 12:54 PM, uǝlƃ ↙↙↙ wrote: > So, I'm trying to learn Rust. And in thinking about the ontological status of > mathematical representations of waves (https://arxiv.org/abs/2101.10873), I > figured I'd validate Euler's identity: > > fn main() { > let e = num::complex::Complex::new(std::f32::consts::E,0.); > let e2ip = e.powc(num::complex::Complex::new(0.,std::f32::consts::PI)); > let i = num::complex::Complex::new(0.,1.); > println!("ln(e^iπ) = {}",e2ip.ln()); > println!("ln(-1) = {}", i.powi(2).ln()); > } > $ cargo run > ln(e^iπ) = 0+3.1415925i > ln(-1) = 0+3.141592653589793i > > I don't have any idea if that's a reasonable way to do that, since I'm > ignorant of Rust. But it's interesting to contrast it with R and Sage: > > $ Rscript -e "log(exp(1)^((0+1i)*pi));log((0+1i)^2)" > [1] 0+3.141593i > [1] 0+3.141593i > > sage: numerical_approx(ln(e^(i*pi)));numerical_approx(ln(i^2)) > 3.14159265358979*I > 3.14159265358979*I > > The precision difference between the 2 results in Rust is interesting. It's > the same if I use powf() instead of powi(). Any clues? Or should I simply > RTFM? > -- ↙↙↙ uǝlƃ - .... . -..-. . -. -.. -..-. .. ... -..-. .... . .-. . FRIAM Applied Complexity Group listserv Zoom Fridays 9:30a-12p Mtn GMT-6 bit.ly/virtualfriam un/subscribe http://redfish.com/mailman/listinfo/friam_redfish.com FRIAM-COMIC http://friam-comic.blogspot.com/ archives: http://friam.471366.n2.nabble.com/
