/**
* @license
* Copyright The Closure Library Authors.
* SPDX-License-Identifier: Apache-2.0
*/
goog.module('goog.math.interpolator.Spline1Test');
goog.setTestOnly();
const Spline1 = goog.require('goog.math.interpolator.Spline1');
const testSuite = goog.require('goog.testing.testSuite');
testSuite({
testSpline() {
// Test special case with no data to interpolate.
let x = [];
let y = [];
let interp = new Spline1();
interp.setData(x, y);
assertTrue(isNaN(interp.interpolate(1)));
// Test special case with 1 data point.
x = [0];
y = [2];
interp = new Spline1();
interp.setData(x, y);
assertRoughlyEquals(2, interp.interpolate(1), 1e-4);
// Test special case with 2 data points.
x = [0, 1];
y = [2, 5];
interp = new Spline1();
interp.setData(x, y);
assertRoughlyEquals(3.5, interp.interpolate(.5), 1e-4);
// Test special case with 3 data points.
x = [0, 1, 2];
y = [2, 5, 4];
interp = new Spline1();
interp.setData(x, y);
assertRoughlyEquals(4, interp.interpolate(.5), 1e-4);
assertRoughlyEquals(-1, interp.interpolate(3), 1e-4);
// Test general case.
x = [0, 1, 3, 6, 7];
y = [0, 0, 0, 0, 0];
for (let i = 0; i < x.length; ++i) {
y[i] = Math.sin(x[i]);
}
interp = new Spline1();
interp.setData(x, y);
const xi = [0, 0.5, 1, 2, 3, 4, 5, 6, 7];
const expected =
[0, 0.5775, 0.8415, 0.7047, 0.1411, -0.3601, -0.55940, -0.2794, 0.6570];
const result = [0, 0, 0, 0, 0, 0, 0, 0, 0];
for (let i = 0; i < xi.length; ++i) {
result[i] = interp.interpolate(xi[i]);
}
assertElementsRoughlyEqual(expected, result, 1e-4);
},
testOutOfBounds() {
const x = [0, 1, 2, 4];
const y = [2, 5, 4, 1];
const interp = new Spline1();
interp.setData(x, y);
assertRoughlyEquals(-7.75, interp.interpolate(-1), 1e-4);
assertRoughlyEquals(4.5, interp.interpolate(5), 1e-4);
},
testInverse() {
const x = [0, 1, 3, 6, 7];
const y = [0, 2, 7, 8, 10];
const interp = new Spline1();
interp.setData(x, y);
const invInterp = interp.getInverse();
const xi = [0, 0.5, 1, 2, 3, 4, 5, 6, 7];
const yi = [0, 0.8159, 2, 4.7892, 7, 7.6912, 7.6275, 8, 10];
const expectedX = [0, 0.8142, 1, 0.2638, 3, 5.0534, 4.8544, 6, 7];
const resultX = [0, 0, 0, 0, 0, 0, 0, 0, 0];
const resultY = [0, 0, 0, 0, 0, 0, 0, 0, 0];
for (let i = 0; i < xi.length; ++i) {
resultY[i] = interp.interpolate(xi[i]);
resultX[i] = invInterp.interpolate(yi[i]);
}
assertElementsRoughlyEqual(expectedX, resultX, 1e-4);
assertElementsRoughlyEqual(yi, resultY, 1e-4);
},
});