60 lines
1.4 KiB
Common Lisp
60 lines
1.4 KiB
Common Lisp
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#!/usr/bin/env conlang-run
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//! Square root approximation, and example applications
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/// A really small nonzero number
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const EPSILON: f64 // = 8.854... * 10^-12
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= 88541878188 as f64
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/ 10000000000 as f64
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/ 1000000000000 as f64;
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/// Calcuates the absolute value of a number
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fn f64_abs(n: f64) -> f64 {
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let n = n as f64
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if n < (0 as f64) { -n } else { n }
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}
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/// Square root approximation using Newton's method
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fn sqrt(n: f64) -> f64 {
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let n = n as f64
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if n < 0 as f64 {
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return 0 as f64 / 0 as f64 // TODO: NaN constant
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}
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if n == 0 as f64 {
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return 0 as f64
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}
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let z = n
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loop {
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let adj = (z * z - n) / (2 as f64 * z)
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z -= adj
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if adj.f64_abs() < EPSILON {
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break z;
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}
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}
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}
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/// Pythagorean theorem: a² + b² = c²
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fn pythag(a: f64, b: f64) -> f64 {
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sqrt(a * a + b * b)
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}
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/// Quadratic formula: (-b ± √(b² - 4ac)) / 2a
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fn quadratic(a: f64, b: f64, c: f64) -> (f64, f64) {
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let a = a as f64; let b = b as f64; let c = c as f64;
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(
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(-b + sqrt(b * b - 4 as f64 * a * c)) / 2 as f64 * a,
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(-b - sqrt(b * b - 4 as f64 * a * c)) / 2 as f64 * a,
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)
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}
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fn main() {
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for i in 0..10 {
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println("sqrt(",i,") ≅ ",sqrt(i))
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}
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println("\nPythagorean Theorem")
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println("Hypotenuse of ⊿(5, 12): ", pythag(5, 12))
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println("\nQuadratic formula")
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println("Roots of 10x² + 4x - 1: ", quadratic(10, 44, -1))
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}
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