Elliptic curve arithmetic: Difference between revisions
no edit summary
m (→{{header|Phix}}: added syntax colouring, marked p2js compatible) |
No edit summary |
||
Line 2,228:
show "a + b + d = " [add $a [add $b $d]]
show "a * 12345 = " [multiply $a 12345]</lang>
{{out}}
<pre>
a = (-1.817, 1.000)
b = (-1.442, 2.000)
c = a + b = (10.375, -33.525)
d = -c = (10.375, 33.525)
c + d = Zero
a + b + d = Zero
a * 12345 = (10.759, 35.387)
</pre>
=={{header|Vlang}}==
{{trans|go}}
<lang vlang>import math
const b_coeff = 7
struct Pt {
x f64
y f64
}
fn zero() Pt {
return Pt{math.inf(1), math.inf(1)}
}
fn is_zero(p Pt) bool {
return p.x > 1e20 || p.x < -1e20
}
fn neg(p Pt) Pt {
return Pt{p.x, -p.y}
}
fn dbl(p Pt) Pt {
if is_zero(p) {
return p
}
l := (3 * p.x * p.x) / (2 * p.y)
x := l*l - 2*p.x
return Pt{
x: x,
y: l*(p.x-x) - p.y,
}
}
fn add(p Pt, q Pt) Pt {
if p.x == q.x && p.y == q.y {
return dbl(p)
}
if is_zero(p) {
return q
}
if is_zero(q) {
return p
}
l := (q.y - p.y) / (q.x - p.x)
x := l*l - p.x - q.x
return Pt{
x: x,
y: l*(p.x-x) - p.y,
}
}
fn mul(mut p Pt, n int) Pt {
mut r := zero()
for i := 1; i <= n; i <<= 1 {
if i&n != 0 {
r = add(r, p)
}
p = dbl(p)
}
return r
}
fn show(s string, p Pt) {
print("$s")
if is_zero(p) {
println("Zero")
} else {
println("(${p.x:.3f}, ${p.y:.3f})")
}
}
fn from_y(y f64) Pt {
return Pt{
x: math.cbrt(y*y - b_coeff),
y: y,
}
}
fn main() {
mut a := from_y(1)
b := from_y(2)
show("a = ", a)
show("b = ", b)
c := add(a, b)
show("c = a + b = ", c)
d := neg(c)
show("d = -c = ", d)
show("c + d = ", add(c, d))
show("a + b + d = ", add(a, add(b, d)))
show("a * 12345 = ", mul(mut a, 12345))
}</lang>
{{out}}
<pre>
| |||