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I am working with multivariate polynomials, e.g.

Expand[Normal[Series[d/Sqrt[(1 - x^2 + y^2)], {x, 0, 5}, {y, 0, 5}]]]

which for this example results in

$\frac{105 x^4 y^4}{64}-\frac{15 x^4 y^2}{16}+\frac{3 x^4}{8}+\frac{15 x^2 y^4}{16}-\frac{3 x^2 y^2}{4}+\frac{x^2}{2}+\frac{3 y^4}{8}-\frac{y^2}{2}+1$

How can truncate the polynomial to a "combined degree" $d\leq i+j, x^iy^j$?

Expected result for the given example and $d=5$:

$\frac{3 x^4}{8}-\frac{3 x^2 y^2}{4}+\frac{x^2}{2}+\frac{3 y^4}{8}-\frac{y^2}{2}+1$


marked as duplicate by J. M. is away May 29 '17 at 11:57

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • $\begingroup$ By modifying the answer to this question you might be able to get what you want. $\endgroup$ – Milad P. May 30 '17 at 9:28
  • $\begingroup$ @MiladP. the answer linked as duplicate is exactly what I wanted. I was just unable to find the answer using google or the site search because the title of the duplicate is bad. $\endgroup$ – R D May 30 '17 at 11:59

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