/**
* @license
* Copyright The Closure Library Authors.
* SPDX-License-Identifier: Apache-2.0
*/
goog.module('goog.math.interpolator.Linear1Test');
goog.setTestOnly();
const Linear1 = goog.require('goog.math.interpolator.Linear1');
const testSuite = goog.require('goog.testing.testSuite');
testSuite({
testLinear() {
// Test special case with no data to interpolate.
let x = [];
let y = [];
let interp = new Linear1();
interp.setData(x, y);
assertTrue(isNaN(interp.interpolate(1)));
// Test special case with 1 data point.
x = [0];
y = [3];
interp = new Linear1();
interp.setData(x, y);
assertRoughlyEquals(3, interp.interpolate(1), 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 Linear1();
interp.setData(x, y);
const xi = [0, 0.5, 1, 2, 3, 4, 5, 6, 7];
const expected =
[0, 0.4207, 0.8415, 0.4913, 0.1411, 0.0009, -0.1392, -0.2794, 0.657];
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];
const y = [2, 5, 4];
const interp = new Linear1();
interp.setData(x, y);
assertRoughlyEquals(interp.interpolate(-1), -1, 1e-4);
assertRoughlyEquals(interp.interpolate(4), 2, 1e-4);
},
testInverse() {
const x = [0, 1, 3, 6, 7];
const y = [0, 2, 7, 8, 10];
const interp = new Linear1();
interp.setData(x, y);
const invInterp = interp.getInverse();
const xi = [0, 0.5, 1, 2, 3, 4, 5, 6, 7];
const yi = [0, 1, 2, 4.5, 7, 7.3333, 7.6667, 8, 10];
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(xi, resultX, 1e-4);
assertElementsRoughlyEqual(yi, resultY, 1e-4);
},
});