v/vlib/math/fractions/fraction.v

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// Copyright (c) 2019-2020 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
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module fractions
import math
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import math.bits
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// Fraction Struct
struct Fraction {
n i64
d i64
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}
// A factory function for creating a Fraction, adds a boundary condition
pub fn fraction(n i64, d i64) Fraction{
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if d != 0 {
return Fraction{n, d}
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}
else {
panic('Denominator cannot be zero')
}
}
// To String method
pub fn (f Fraction) str() string {
return '$f.n/$f.d'
}
// Fraction add using operator overloading
pub fn (f1 Fraction) + (f2 Fraction) Fraction {
if f1.d == f2.d {
return Fraction{f1.n + f2.n, f1.d}
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}
else {
return Fraction{(f1.n * f2.d) + (f2.n * f1.d), f1.d * f2.d}
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}
}
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// Fraction subtract using operator overloading
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pub fn (f1 Fraction) - (f2 Fraction) Fraction {
if f1.d == f2.d {
return Fraction{f1.n - f2.n, f1.d}
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}
else {
return Fraction{(f1.n * f2.d) - (f2.n * f1.d), f1.d * f2.d}
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}
}
// Fraction multiply using operator overloading
// pub fn (f1 Fraction) * (f2 Fraction) Fraction {
// return Fraction{f1.n * f2.n,f1.d * f2.d}
// }
// Fraction divide using operator overloading
// pub fn (f1 Fraction) / (f2 Fraction) Fraction {
// return Fraction{f1.n * f2.d,f1.d * f2.n}
// }
// Fraction add method
pub fn (f1 Fraction) add(f2 Fraction) Fraction {
return f1 + f2
}
// Fraction subtract method
pub fn (f1 Fraction) subtract(f2 Fraction) Fraction {
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return f1 - f2
}
// Fraction multiply method
pub fn (f1 Fraction) multiply(f2 Fraction) Fraction {
return Fraction{f1.n * f2.n, f1.d * f2.d}
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}
// Fraction divide method
pub fn (f1 Fraction) divide(f2 Fraction) Fraction {
return Fraction{f1.n * f2.d, f1.d * f2.n}
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}
// Fraction reciprocal method
pub fn (f1 Fraction) reciprocal() Fraction {
if f1.n == 0 { panic('Denominator cannot be zero') }
return Fraction{f1.d, f1.n}
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}
// Fraction method which gives greatest common divisor of numerator and denominator
pub fn (f1 Fraction) gcd() i64 {
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return math.gcd(f1.n, f1.d)
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}
// Fraction method which reduces the fraction
pub fn (f1 Fraction) reduce() Fraction {
cf := f1.gcd()
return Fraction{f1.n / cf, f1.d / cf}
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}
// Converts Fraction to decimal
pub fn (f1 Fraction) f64() f64 {
return f64(f1.n) / f64(f1.d)
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}
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// 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
}
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// Compares two Fractions
pub fn (f1 Fraction) equals(f2 Fraction) bool {
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if safe_to_multiply(f1.n, f2.d) && safe_to_multiply(f2.n, f1.d) {
return (f1.n * f2.d) == (f2.n * f1.d)
}
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r1 := f1.reduce()
r2 := f2.reduce()
return (r1.n == r2.n) && (r1.d == r2.d)
}