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 Apr 8 awarded Nice Answer Feb 28 comment How to define a function something like f[u_[x_]] := x, but defining a function that takes as a second argument the derivative of the first is more involved. Jan 31 awarded Nice Answer Jan 31 comment Does Mathematica support Laguerre Polynomials of Matrix Argument? So operationally, you can think of MatrixFunction as taking a scalar function as the first arg, finding its series expansion, then using that to turn it into a matrix function and finally applying that to the second arg. If the second arg can eg be diagonalised via an orthogonal transformation, all you'd need to do do the transformation, apply a polynomial to the eigenvals and undo the transformation. Jan 31 comment Does Mathematica support Laguerre Polynomials of Matrix Argument? Oops you're right, LaguerreL is Listable so it just threads. OK, this does what you want I think: m = # + Transpose@# &@RandomReal[{-1, 1}, {10, 10}]; MatrixFunction[LaguerreL[3.2, #] &, m] (the idea is that MatrixFunction takes a scalar fn as the first arg, turns it into a matrix function and applies it to the second argument). Unless you actually do want a scalar as the output but then you need to explain how you want to get it. Jan 30 comment Does Mathematica support Laguerre Polynomials of Matrix Argument? it produces a 10 by 10 matrix of elements drawn from a uniform random distribution and then adds it to its transpose. I just wanted a symmetric matrix. Jan 30 comment Does Mathematica support Laguerre Polynomials of Matrix Argument? Apparently yes, eg m = # + Transpose@# &@RandomReal[{-1, 1}, {10, 10}]; LaguerreL[3.2, m] seems to work. In general you could also use MatrixFunction for this sort of thing. Jan 20 comment Why is (-1.)^2. a complex number @xslittlegrass I see. No idea then. Jan 20 comment Why is (-1.)^2. a complex number Look: Plot[{Re@#, Im@#} &@((-1)^x), {x, 1.5, 2.5}] Jan 17 awarded Yearling Jan 7 awarded Nice Answer Dec 16 comment Can't type in notebook in version 10 The same thing happened to me a couple of times (also on OS X). Quitting Mathematica and restarting it fixed it both times. Interestingly, when I quit, it put up a dialog to save a few of the notebooks, and there I could interact with it (to click on yes or no). Very strange. Nov 23 awarded Good Answer Oct 27 awarded Good Question Oct 14 revised Graph showing valid English words obtained by insertion of single characters formatting Sep 30 awarded Explainer Sep 19 awarded Generalist Sep 15 awarded Nice Question Aug 29 comment Integral of x^p Oh right that's why it doesn't work in mathematica. Oops, pattern recognised the wrong thing, I'm an idiot sorry. Aug 29 comment Integral of x^p Actually the log is recovered in the limit. It's just that mathematica doesn't recover it correctly.