public static Expression Build(Expression expr)
{
if (expr is NegatedExpression negated)
{
return(negated.Expression);
}
else if (expr is ConstantExpression constant)
{
return(-constant.Value);
}
else if (expr is AdditionExpression addition)
{
return(AdditionExpression.Build(-addition.Constant, addition.VariableParts.Select(x => NegatedExpression.Build(x))));
}
else if (expr is MultiplicationExpression multiplication)
{
return(MultiplicationExpression.Build(-multiplication.Coefficient, multiplication.VariableParts));
}
else
{
return(new NegatedExpression(expr));
}
}
public override Expression FindDerivative() => AdditionExpression.Build(VariableParts.Select(x => x.FindDerivative() * MultiplicationExpression.Build(VariableParts.Where(y => y != x)))) * Coefficient;
/// <summary> /// Binary multiplication of expressions. /// </summary> /// <param name="first">Left-side expression.</param> /// <param name="second">Right-side expression.</param> /// <returns>Returns the result of multiplying the operand expressions.</returns> public static Expression operator *(Expression first, Expression second) => MultiplicationExpression.Build(first, second);