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math.fractions: improve `.equals()`

pull/4788/head
Hungry Blue Dev 2020-05-08 18:09:23 +05:30 committed by GitHub
parent e08566d571
commit dbb3c2a4cd
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1 changed files with 19 additions and 0 deletions
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19
vlib/math/fractions/fraction.v
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@ -5,6 +5,7 @@
module fractions module fractions
import math import math
import math.bits
// Fraction Struct // Fraction Struct
struct Fraction { struct Fraction {
@ -99,8 +100,26 @@ pub fn (f1 Fraction) f64() f64 {
return f64(f1.n) / f64(f1.d) return f64(f1.n) / f64(f1.d)
} }
// Returns the absolute value of an i64
fn abs(num i64) i64 {
if num < 0 {
return -num
} else {
return num
}
}
// Two integers are safe to multiply when their bit lengths
// sum up to less than 64 (conservative estimate).
fn safe_to_multiply(a, b i64) bool {
return (bits.len_64(abs(a)) + bits.len_64(abs(b))) < 64
}
// Compares two Fractions // Compares two Fractions
pub fn (f1 Fraction) equals(f2 Fraction) bool { pub fn (f1 Fraction) equals(f2 Fraction) bool {
if safe_to_multiply(f1.n, f2.d) && safe_to_multiply(f2.n, f1.d) {
return (f1.n * f2.d) == (f2.n * f1.d)
}
r1 := f1.reduce() r1 := f1.reduce()
r2 := f2.reduce() r2 := f2.reduce()
return (r1.n == r2.n) && (r1.d == r2.d) return (r1.n == r2.n) && (r1.d == r2.d)