// check equality operator
public void CheckEquality()
{
// create two equal FiniteDifference
FiniteDifference l = FiniteDifference.GetFiniteDifferenceByOrder(2);
FiniteDifference r = FiniteDifference.GetFiniteDifferenceByOrder(2);
Assert.True(l == r);
// REMOVED AS FiniteDifference indexer changed to read-only
// *****************************************************************************************************
////////// change coefficient
////////l[0] = 2;
////////Assert.False(l == r);
////////// revert coefficient
////////l[0] = 1;
////////Assert.True(l == r);
////////// create FiniteDifference with different order
////////r = FiniteDifference.GetFiniteDifferenceByOrder(3);
////////Assert.False(l == r);
////////// change right's coefficients to match left's
////////r[0] = 1;
////////r[1] = -2;
////////r[2] = 1;
////////Assert.False(l == r);
// *****************************************************************************************************
// create FiniteDifference with the same order but another minimumH
r = FiniteDifference.GetFiniteDifferenceByOrderAndMinH(2, 1);
Assert.False(l == r);
// create same FiniteDifference
l = FiniteDifference.GetFiniteDifferenceByOrderAndMinH(2, 1);
Assert.True(l == r);
}
// check parsing simple du
public void Order1CheckWithoutH()
{
FiniteDifference goodDifference = FiniteDifference.GetFiniteDifferenceByOrder(1);
string s = "du(x)";
Assert.True(FiniteDifference.Parse(s) == goodDifference);
}
// check simple u(x)
public void NodNoH()
{
FiniteDifference goodDifference = FiniteDifference.GetFiniteDifferenceByOrder(0);
string s = "u(x)";
Assert.True(FiniteDifference.Parse(s) == goodDifference);
}
// just create FiniteDifference with minimumH=0 and check order, minimumH and maximumH
public void CheckOrderAfterCreating(int order)
{
FiniteDifference dif = FiniteDifference.GetFiniteDifferenceByOrder(order);
Assert.Equal(order, dif.Order);
Assert.Equal(0, dif.MinimumH);
Assert.Equal(order, dif.MaximumH);
}
// check returning null on creating bad order
public void CheckBadOrderCreating()
{
Assert.Null(FiniteDifference.GetFiniteDifferenceByOrder(-1));
Assert.Null(0 * FiniteDifference.GetFiniteDifferenceByOrder(1));
// check summations
Assert.Null(FiniteDifference.GetFiniteDifferenceByOrder(3) - FiniteDifference.GetFiniteDifferenceByOrder(3));
Assert.Null(FiniteDifference.GetFiniteDifferenceByOrderAndMinH(3, 2) -
FiniteDifference.GetFiniteDifferenceByOrderAndMinH(2, 3) +
FiniteDifference.GetFiniteDifferenceByOrderAndMinH(2, 2));
}
// check parsing d^nu and dnu
public void OrderCheckWithoutH(int order)
{
FiniteDifference goodDifference = FiniteDifference.GetFiniteDifferenceByOrder(order);
// check d^nu
string s = $"d^{order}u(x)";
Assert.True(FiniteDifference.Parse(s) == goodDifference);
// check dnu
s = $"d{order}u(x)";
Assert.True(FiniteDifference.Parse(s) == goodDifference);
}
public void CheckOperationsWithNotFiniteDifference()
{
// create normal FiniteDifference and two non-FiniteDifferences
FiniteDifference order11 = FiniteDifference.GetFiniteDifferenceByOrder(1);
FiniteDifference not1 = FiniteDifference.GetFiniteDifferenceByOrder(-1);
FiniteDifference not2 = FiniteDifference.GetFiniteDifferenceByOrder(-1);
// check equality
Assert.True(order11 != not1);
Assert.True(not1 == not2);
// check multiplication
Assert.Null(not1 * 2);
// check summation
Assert.True(order11 == order11 + not1);
Assert.Null(not1 + not2);
}
// check summation of multiple summands with coefficients
public void CheckSummation()
{
string s = " d3 u(x-2*h) - 2 * du(x-h) + u(x+2*h) - 1 * d^2 u(x) ";
Assert.True(FiniteDifference.GetFiniteDifferenceByOrderAndMinH(3, -2)
- 2 * FiniteDifference.GetFiniteDifferenceByOrderAndMinH(1, -1)
+ FiniteDifference.GetFiniteDifferenceByOrderAndMinH(0, 2)
- FiniteDifference.GetFiniteDifferenceByOrder(2)
== DifferenceExpressionEvaluator.Evaluate(s));
s = " - d^3u(x-2*h) - 2 * du(x-h) + u(x+2*h) - 1 * d^2 u(x) ";
Assert.True(-FiniteDifference.GetFiniteDifferenceByOrderAndMinH(3, -2)
- 2 * FiniteDifference.GetFiniteDifferenceByOrderAndMinH(1, -1)
+ FiniteDifference.GetFiniteDifferenceByOrderAndMinH(0, 2)
- FiniteDifference.GetFiniteDifferenceByOrder(2)
== DifferenceExpressionEvaluator.Evaluate(s));
}