public SymbolFunction D(int index = 0)
{
var f = new SymbolFunction(this, Arguments);
f.Derivatives[index]++;
return(f);
}
public SymbolFunction(SymbolFunction f, params Expression[] args) :
base(args)
{
this.name = f.Name;
if (args.Length <= f.Derivatives.Length)
{
Derivatives = f.Derivatives.Take(args.Length).ToArray();
}
else
{
Derivatives = f.Derivatives
.Concat(new int[args.Length - f.Derivatives.Length])
.ToArray();
}
var lastD = Array.FindLastIndex(Derivatives, d => d != 0);
if (lastD >= args.Length)
{
throw new ArgumentException();
}
}
