I am trying to perform a series expansion of a function of 6 variables, and I would like to do this to 4th order.
I know the form of the Series command, and I can easily expand the equation to find terms containing each of the variables to the required order.
My problem is that some of these terms are of the form K.x^4.y^4, which is correct in that it only contains x and y to the fourth order, but is not what I would like in that I tend to think of this term as being of 8th order.
Is there any way of limiting the output of Series, or perhaps writing a rule to operate on its output, to limit the *total* power of each term to 4th order?
Note that a simple rule adding each of the powers in the FullForm will not work as I have some constants that also appear to the 2nd, 3rd, or 4th, power (e.g. K^2.x^2.y^2 is allowed).
Many thanks for any help you can offer.