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<!DOCTYPE html>
<html>
<!--
Copyright 2011 The Closure Library Authors. All Rights Reserved.

Use of this source code is governed by the Apache License, Version 2.0.
See the COPYING file for details.
-->
<head>
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>Closure Unit Tests - goog.math.interpolator.Spline1</title>
<script src="../../base.js"></script>
<script>
  goog.require('goog.math.interpolator.Spline1');
  goog.require('goog.testing.jsunit');
</script>
</head>
<body>
<script>

  function testSpline() {
    // Test special case with no data to interpolate.
    var x = [];
    var y = [];
    var interp = new goog.math.interpolator.Spline1();
    interp.setData(x, y);
    assertTrue(isNaN(interp.interpolate(1)));

    // Test special case with 1 data point.
    x = [0];
    y = [2];
    interp = new goog.math.interpolator.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 goog.math.interpolator.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 goog.math.interpolator.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 (var i = 0; i < x.length; ++i) {
      y[i] = Math.sin(x[i]);
    }
    interp = new goog.math.interpolator.Spline1();
    interp.setData(x, y);

    var xi = [0, 0.5, 1, 2, 3, 4, 5, 6, 7];
    var expected = [0, 0.5775, 0.8415, 0.7047, 0.1411, -0.3601, -0.55940,
      -0.2794, 0.6570];
    var result = [0, 0, 0, 0, 0, 0, 0, 0, 0];
    for (var i = 0; i < xi.length; ++i) {
      result[i] = interp.interpolate(xi[i]);
    }
    assertElementsRoughlyEqual(expected, result, 1e-4);
  };


  function testOutOfBounds() {
    var x = [0, 1, 2, 4];
    var y = [2, 5, 4, 1];
    var interp = new goog.math.interpolator.Spline1();
    interp.setData(x, y);
    assertRoughlyEquals(-7.75, interp.interpolate(-1), 1e-4);
    assertRoughlyEquals(4.5, interp.interpolate(5), 1e-4);
  };


  function testInverse() {
    var x = [0, 1, 3, 6, 7];
    var y = [0, 2, 7, 8, 10];

    var interp = new goog.math.interpolator.Spline1();
    interp.setData(x, y);
    var invInterp = interp.getInverse();

    var xi = [0, 0.5, 1, 2, 3, 4, 5, 6, 7];
    var yi = [0, 0.8159, 2, 4.7892, 7, 7.6912, 7.6275, 8, 10];
    var expectedX = [0, 0.8142, 1, 0.2638, 3, 5.0534, 4.8544, 6, 7];
    var resultX = [0, 0, 0, 0, 0, 0, 0, 0, 0];
    var resultY = [0, 0, 0, 0, 0, 0, 0, 0, 0];
    for (var 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);
  };

</script>
</body>