public void NumbersShouldBeOrderedFirstInCommutativeVariadicOperations()
{
var t = Var("𝓉");
var addition = SymbolicExpression.Add(ImmutableArray.Create(t, Pi, 735, Pow(t, 2)));
Assert.Equal(735 + Pi + t + Pow(t, 2), addition);
Assert.Equal(735, ((VariadicOperationExpression)addition).Operands[0]);
var multiplication = SymbolicExpression.Multiply(ImmutableArray.Create(t, Pow(t, 2), 78, Pow(E, t), Pi));
Assert.Equal(78 * Pi * t * Pow(t, 2) * Pow(E, t), multiplication);
Assert.Equal(78, ((VariadicOperationExpression)multiplication).Operands[0]);
}
public void AdditionsShouldMerge()
{
var x = Var("𝓍");
var y = Var("𝓎");
var z = Var("𝓏");
var w = Var("𝓌");
var expected = SymbolicExpression.Add(ImmutableArray.Create(x, y, z, w));
Assert.Equal(expected, x + (y + (z + w)));
Assert.Equal(expected, x + ((y + z) + w));
Assert.Equal(expected, (x + y) + (z + w));
Assert.Equal(expected, (x + (y + z)) + w);
Assert.Equal(expected, ((x + y) + z) + w);
}
public static SymbolicExpression GetTaylor(int k, SymbolicExpression symbol, SymbolicExpression a, SymbolicExpression x)
{
int factorial = 1;
SymbolicExpression accumulator = SymbolicExpression.Zero;
SymbolicExpression derivative = x;
for (int i = 0; i < k; i++)
{
var subs = derivative.Substitute(symbol, a);
derivative = derivative.Differentiate(symbol);
accumulator = accumulator.Add(subs / factorial * (symbol.Subtract(a)).Pow(i));
factorial *= (i + 1);
}
return accumulator.Expand();
}