public void Gradient()
{
var f = new PiecewiseLinearFunction <double>(new List <IVector <double> >()
{
new Vector <double>(1d), new Vector <double>(2d)
});
var grad = f.Gradient(new Vector <double>(new[] { 0d, 0d, 3d, 3d, 10d, 10d }),
new Vector <double>(0.5d));
Assert.True(grad.Count == 6);
Assert.True(grad.Skip(2).All(x => Math.Abs(x) < 1e-14));
Assert.True(Math.Abs(grad[0] - 0.5) < 1e-14);
Assert.True(Math.Abs(grad[1] - 1) < 1e-14);
grad = f.Gradient(new Vector <double>(new[] { 0d, 0d, 3d, 3d, 10d, 10d }),
new Vector <double>(1.5d));
Assert.True(grad.Count == 6);
Assert.True(grad.Take(2).All(x => Math.Abs(x) < 1e-14));
Assert.True(grad.TakeLast(2).All(x => Math.Abs(x) < 1e-14));
Assert.True(Math.Abs(grad[2] - 1.5) < 1e-14);
Assert.True(Math.Abs(grad[3] - 1) < 1e-14);
grad = f.Gradient(new Vector <double>(new[] { 0d, 0d, 3d, 3d, 10d, 10d }),
new Vector <double>(3d));
Assert.True(grad.Count == 6);
Assert.True(grad.Take(4).All(x => Math.Abs(x) < 1e-14));
Assert.True(Math.Abs(grad[4] - 3) < 1e-14);
Assert.True(Math.Abs(grad[5] - 1) < 1e-14);
grad = f.Gradient(new Vector <double>(new[] { 0d, 0d, 3d, 3d, 10d, 10d }),
new Vector <double>(2d));
Assert.True(grad.Count == 6);
Assert.True(grad.Count == 6);
Assert.True(grad.Take(4).All(x => Math.Abs(x) < 1e-14));
Assert.True(Math.Abs(grad[4] - 2) < 1e-14);
Assert.True(Math.Abs(grad[5] - 1) < 1e-14);
Assert.True(1e-14 > 6 - f.Value(new Vector <double>(new[] { 0d, 0d, 3d, 3d, 10d, 10d }),
new Vector <double>(new[] { 1d })));
grad = f.Gradient(new Vector <double>(new[] { 0d, 0d, 3d, 3d, 10d, 10d }),
new Vector <double>(1.5d));
Assert.True(grad.Count == 6);
Assert.True(grad.Take(2).All(x => Math.Abs(x) < 1e-14));
Assert.True(grad.TakeLast(2).All(x => Math.Abs(x) < 1e-14));
Assert.True(Math.Abs(grad[2] - 1.5) < 1e-14);
Assert.True(Math.Abs(grad[3] - 1) < 1e-14);
}
