Tropical algebra overloading: Difference between revisions
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max tropical comparison of 5 (x) with (+)(8,7) compared to
(x)(5,8) with (+) (x)(5,7) ───► true
</pre>
=={{header|Vlang}}==
{{trans|Go}}
Vlang doesn't support operator overloading so we need to use functions instead.
<lang vlang>import math
const (
minus_inf = math.inf(-1)
)
struct MaxTropical { r f64 }
fn new_max_tropical(r f64) ?MaxTropical {
if math.is_inf(r, 1) || math.is_nan(r) {
return error("Argument must be a real number or negative infinity.")
}
return MaxTropical{r}
}
fn (t MaxTropical) eq(other MaxTropical) bool {
return t.r == other.r
}
// equivalent to ⊕ operator
fn (t MaxTropical) add(other MaxTropical) ?MaxTropical {
if t.r == minus_inf {
return other
}
if other.r == minus_inf {
return t
}
return new_max_tropical(math.max(t.r, other.r))
}
// equivalent to ⊗ operator
fn (t MaxTropical) mul(other MaxTropical) ?MaxTropical {
if t.r == 0 {
return other
}
if other.r == 0 {
return t
}
return new_max_tropical(t.r + other.r)
}
// exponentiation fntion
fn (t MaxTropical) pow(e int) ?MaxTropical {
if e < 1 {
return error("Exponent must be a positive integer.")
}
if e == 1 {
return t
}
mut p := t
for i := 2; i <= e; i++ {
p = p.mul(t)?
}
return p
}
fn (t MaxTropical) str() string {
return '${t.r}'
}
fn main() {
// 0 denotes ⊕ and 1 denotes ⊗
data := [
[2.0, -2, 1],
[-0.001, minus_inf, 0],
[0.0, minus_inf, 1],
[1.5, -1, 0],
[-0.5, 0, 1],
]
for d in data {
a := new_max_tropical(d[0])?
b := new_max_tropical(d[1])?
c := a.add(b)?
m := a.mul(b)?
if d[2] == 0 {
println("$a ⊕ $b = $c")
} else {
println("$a ⊗ $b = $m")
}
}
c := new_max_tropical(5)?
println("$c ^ 7 = ${c.pow(7)}")
d := new_max_tropical(8)?
e := new_max_tropical(7)?
f := c.mul(d.add(e)?)?
g := c.mul(d)?.add(c.mul(e)?)?
println("$c ⊗ ($d ⊕ $e) = $f")
println("$c ⊗ $d ⊕ $c ⊗ $e = $g")
println("$c ⊗ ($d ⊕ $e) == $c ⊗ $d ⊕ $c ⊗ $e is ${f.eq(g)}")
}</lang>
{{out}}
<pre>
2 ⊗ -2 = 0
-0.001 ⊕ -inf = -0.001
0 ⊗ -inf = -inf
1.5 ⊕ -1 = 1.5
-0.5 ⊗ 0 = -0.5
5 ^ 7 = Option(35)
5 ⊗ (8 ⊕ 7) = 13
5 ⊗ 8 ⊕ 5 ⊗ 7 = 13
5 ⊗ (8 ⊕ 7) == 5 ⊗ 8 ⊕ 5 ⊗ 7 is true
</pre>
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