Anonymous user
Thiele's interpolation formula: Difference between revisions
Add Swift
Thundergnat (talk | contribs) (Rename Perl 6 -> Raku, alphabetize, minor clean-up) |
(Add Swift) |
||
Line 1,366:
3.14159265358979323846264318595256260456200366896
</pre>
=={{header|Swift}}==
{{trans|Kotlin}}
<lang swift>let N = 32
let N2 = N * (N - 1) / 2
let step = 0.05
var xval = [Double](repeating: 0, count: N)
var tsin = [Double](repeating: 0, count: N)
var tcos = [Double](repeating: 0, count: N)
var ttan = [Double](repeating: 0, count: N)
var rsin = [Double](repeating: .nan, count: N2)
var rcos = [Double](repeating: .nan, count: N2)
var rtan = [Double](repeating: .nan, count: N2)
func rho(_ x: [Double], _ y: [Double], _ r: inout [Double], _ i: Int, _ n: Int) -> Double {
guard n >= 0 else {
return 0
}
guard n != 0 else {
return y[i]
}
let idx = (N - 1 - n) * (N - n) / 2 + i
if r[idx] != r[idx] {
r[idx] = (x[i] - x[i + n]) /
(rho(x, y, &r, i, n - 1) - rho(x, y, &r, i + 1, n - 1)) + rho(x, y, &r, i + 1, n - 2)
}
return r[idx]
}
func thiele(_ x: [Double], _ y: [Double], _ r: inout [Double], _ xin: Double, _ n: Int) -> Double {
guard n <= N - 1 else {
return 1
}
return rho(x, y, &r, 0, n) - rho(x, y, &r, 0, n - 2) + (xin - x[n]) / thiele(x, y, &r, xin, n + 1)
}
for i in 0..<N {
xval[i] = Double(i) * step
tsin[i] = sin(xval[i])
tcos[i] = cos(xval[i])
ttan[i] = tsin[i] / tcos[i]
}
print(String(format: "%16.14f", 6 * thiele(tsin, xval, &rsin, 0.5, 0)))
print(String(format: "%16.14f", 3 * thiele(tcos, xval, &rcos, 0.5, 0)))
print(String(format: "%16.14f", 4 * thiele(ttan, xval, &rtan, 1.0, 0)))
</lang>
{{out}}
<pre>3.14159265358979
3.14159265358979
3.14159265358980</pre>
=={{header|Tcl}}==
| |||