Curve Fitting Visualization
function polynomialRegression2(x, y) {
let n = x.length;
let sumX = 0, sumX2 = 0, sumX3 = 0, sumX4 = 0;
let sumY = 0, sumXY = 0, sumX2Y = 0;
for (let i = 0; i < n; i++) {
let xi = x[i];
let yi = y[i];
let xi2 = xi * xi;
let xi3 = xi2 * xi;
let xi4 = xi3 * xi;
sumX += xi;
sumX2 += xi2;
sumX3 += xi3;
sumX4 += xi4;
sumY += yi;
sumXY += xi * yi;
sumX2Y += xi2 * yi;
}
let A = [
[sumX4, sumX3, sumX2],
[sumX3, sumX2, sumX],
[sumX2, sumX, n]
];
let B = [sumX2Y, sumXY, sumY];
function solveSystem(A, B) {
let det = (A[0][0] * (A[1][1] * A[2][2] – A[1][2] * A[2][1]) –
A[0][1] * (A[1][0] * A[2][2] – A[1][2] * A[2][0]) +
A[0][2] * (A[1][0] * A[2][1] – A[1][1] * A[2][0]));
let A_inv = [
[ (A[1][1] * A[2][2] – A[1][2] * A[2][1]) / det,
-(A[0][1] * A[2][2] – A[0][2] * A[2][1]) / det,
(A[0][1] * A[1][2] – A[0][2] * A[1][1]) / det],
[-(A[1][0] * A[2][2] – A[1][2] * A[2][0]) / det,
(A[0][0] * A[2][2] – A[0][2] * A[2][0]) / det,
-(A[0][0] * A[1][2] – A[0][2] * A[1][0]) / det],
[ (A[1][0] * A[2][1] – A[1][1] * A[2][0]) / det,
-(A[0][0] * A[2][1] – A[0][1] * A[2][0]) / det,
(A[0][0] * A[1][1] – A[0][1] * A[1][0]) / det]
];
let result = [
A_inv[0][0] * B[0] + A_inv[0][1] * B[1] + A_inv[0][2] * B[2],
A_inv[1][0] * B[0] + A_inv[1][1] * B[1] + A_inv[1][2] * B[2],
A_inv[2][0] * B[0] + A_inv[2][1] * B[1] + A_inv[2][2] * B[2]
];
return result;
}
let [a, b, c] = solveSystem(A, B);
return { a, b, c };
}
let x_data = [0.0, 0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875, 1.0];
let y_data = [328.529, 345.116, 367.235, 389.358, 411.71, 423.0, 416.925, 404.9, 395.975];
let coeffs = polynomialRegression2(x_data, y_data);
console.log(`Persamaan regresi: y = ${coeffs.a.toFixed(2)}xยฒ + ${coeffs.b.toFixed(2)}x + ${coeffs.c.toFixed(2)}`);
let x_fit = [];
let y_fit = [];
for (let x = 0; x ({ x: xi, y: y_data[i] })),
backgroundColor: ‘red’
},
{
label: ‘Curve Fitting’,
data: x_fit.map((xi, i) => ({ x: xi, y: y_fit[i] })),
type: ‘line’,
borderColor: ‘blue’,
fill: false
}
]
},
options: {
scales: {
x: { title: { display: true, text: ‘Posisi (m)’ } },
y: { title: { display: true, text: ‘Temperatur (K)’ } }
}
}
});
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