# Second Derivatives - Help.

Posted 8 years ago
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 Hello,I bought the app you for AppStore, I am a customer from Brazil. I could not solve second derivative questions, could you help me?I would like to find the derivatives of a function in shapes: X, Y, XX, XY, YX, YY.Example: F (X, Y) = e ^ (2-x) / Y ^ 2F (x) = F (y) = F (xx) = F (xy) = F (yx) = F (yy) =Can you explain me how to write these formulas in the application? Thanks !!
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Posted 8 years ago
 Hello,and easy extension would be In[31]:= f[x_, y_] := e^(2 - x)/y^2 Table[Derivative[i, j][f][x, y], {i, 0, 2}, {j, 0, 2}] Out[32]= {{e^(2 - x)/y^2, -((2 e^(2 - x))/y^3), (6 e^(2 - x))/ y^4}, {-((e^(2 - x) Log[e])/y^2), (2 e^(2 - x) Log[e])/ y^3, -((6 e^(2 - x) Log[e])/y^4)}, {(e^(2 - x) Log[e]^2)/ y^2, -((2 e^(2 - x) Log[e]^2)/y^3), (6 e^(2 - x) Log[e]^2)/y^4}} 
Posted 8 years ago
 Hi,I do not really understand your question and I do not know what application you are talking about. If you define F[x, y] := Exp[2 - x]/y^2 these lines generate the derivatives that your are looking for: D[F[x, y], #] & /@ {x, y} and D[F[x, y], #[[1]], #[[2]]] & /@ Tuples[{x, y}, 2] There are probably easier ways. If you want to set all of them equal as you appear to suggest in your post you can use: Equal @@ Union[D[F[x, y], #] & /@ {x, y}, D[F[x, y], #[[1]], #[[2]]] & /@ Tuples[{x, y}, 2]] Cheers,MarcoPS: You might also want to use the proper formatting when you post. If you put the formulas in the appropriate code boxes it is easier to reply. Also I am not sure whether the use of capital Y and small y is intentional or just a typo. PPS: I also might be answering something completely wrong, because I do not know what App from the AppStore you are talking about. Is is the Wolfram alpha app?