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Polynomial regression: Difference between revisions
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ReadChar;
END PolynomialRegression.</lang>
=={{header|Nim}}==
{{trans|Kotlin}}
<lang Nim>import lenientops, sequtils, stats, strformat
proc polyRegression(x, y: openArray[int]) =
let xm = mean(x)
let ym = mean(y)
let x2m = mean(x.mapIt(it * it))
let x3m = mean(x.mapIt(it * it * it))
let x4m = mean(x.mapIt(it * it * it * it))
let xym = mean(zip(x, y).mapIt(it[0] * it[1]))
let x2ym = mean(zip(x, y).mapIt(it[0] * it[0] * it[1]))
let sxx = x2m - xm * xm
let sxy = xym - xm * ym
let sxx2 = x3m - xm * x2m
let sx2x2 = x4m - x2m * x2m
let sx2y = x2ym - x2m * ym
let b = (sxy * sx2x2 - sx2y * sxx2) / (sxx * sx2x2 - sxx2 * sxx2)
let c = (sx2y * sxx - sxy * sxx2) / (sxx * sx2x2 - sxx2 * sxx2)
let a = ym - b * xm - c * x2m
func abc(x: int): float = a + b * x + c * x * x
echo &"y = {a} + {b}x + {c}x²\n"
echo " Input Approximation"
echo " x y y1"
for (xi, yi) in zip(x, y):
echo &"{xi:2} {yi:3} {abc(xi):5}"
let x = toSeq(0..10)
let y = [1, 6, 17, 34, 57, 86, 121, 162, 209, 262, 321]
polyRegression(x, y)</lang>
{{out}}
<pre>y = 1.0 + 2.0x + 3.0x²
Input Approximation
x y y1
0 1 1
1 6 6
2 17 17
3 34 34
4 57 57
5 86 86
6 121 121
7 162 162
8 209 209
9 262 262
10 321 321</pre>
=={{header|Octave}}==
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