public void ToTaylorExpansion_2()
{
var power = new PowerFunction { Aparam = 2, Bparam = 3, PowerNumerator = 1, PowerDenominator = 2 };
var expansion = power.ToTaylorExpansion(2).ToList();
expansion.Should().HaveCount(4);
expansion.Select(s => s.PolynomialDegree).Should().ContainInOrder(0, 1, 2, 0);
expansion.Select(s => s.LittleODegree).Should().ContainInOrder(0, 0, 0, 2);
expansion.Select(s => s.Coefficient).Should().ContainInOrder(Math.Pow(3, 0.5), Math.Pow(3, 0.5) * 1.0 / 3.0, Math.Pow(3, 0.5) * -1.0 / 18.0, 1.0);
}
public void ToTaylorExpansion_1()
{
var power = new PowerFunction {Aparam = 2, Bparam = 3, PowerNumerator = 3, PowerDenominator = 1};
var expansion = power.ToTaylorExpansion(7).ToList();
expansion.Should().HaveCount(4);
expansion.Select(s => s.PolynomialDegree).Should().ContainInOrder(0, 1, 2, 3);
expansion.Select(s => s.LittleODegree).Should().OnlyContain(x => x == 0);
expansion.Select(s => s.Coefficient).Should().ContainInOrder(27.0, 54.0, 36.0, 8.0);
}
public static IElementaryFunction ConvertToElementaryFunction(string str)
{
IElementaryFunction function = null;
double[] arr = null;
if (str.Contains("sin"))
{
function = new Sine();
arr = FindParameters(str.Substring(4, str.Count() - 4));
function.Aparam = arr[0];
function.Bparam = arr[1];
}
else if (str.Contains("cos"))
{
function = new Cosine();
arr = FindParameters(str.Substring(4, str.Count() - 4));
function.Aparam = arr[0];
function.Bparam = arr[1];
}
else if (str.Contains("ln"))
{
function = new LogarithmicFunction();
arr = FindParameters(str.Substring(3, str.Count() - 3));
function.Aparam = arr[0];
function.Bparam = arr[1];
}
else if (str.Contains("e^"))
{
function = new ExponentialFunction();
arr = FindParameters(str.Substring(3, str.Count() - 3));
function.Aparam = arr[0];
function.Bparam = arr[1];
}
else if (str.Contains(")^(") || str.Contains("x^(") || str.Contains(")^"))
{
function = new PowerFunction();
int powerPosition = 0;
for (int i = 0; i < str.Count(); i++)
{
if (str[i] == '^')
{
powerPosition = i;
StringBuilder num = new StringBuilder();
StringBuilder den = new StringBuilder();
bool slash = false;
for (int j = i + 1; j < str.Count(); j++)
{
if (str[j] != '/' && str[j] != '(' && str[j] != ')')
{
if (slash == false)
{
num.Append(str[j]);
}
else den.Append(str[j]);
}
else if (str[j] == '/')
{
slash = true;
}
}
if (slash == false)
{
((PowerFunction)function).PowerDenominator = 1;
}
else
{
((PowerFunction)function).PowerDenominator = int.Parse(den.ToString());
}
((PowerFunction)function).PowerNumerator = int.Parse(num.ToString());
}
}
int beginPosition = 0;
if (str[0] == '(')
{
beginPosition = 1;
}
arr = FindParameters(str.Substring(beginPosition, powerPosition - beginPosition));
function.Aparam = arr[0];
function.Bparam = arr[1];
}
return function;
}
