# Find the inverse of function h by a numerical way ?

Posted 4 months ago
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 Hello guys, Please I have a question: I need to know the inverse of function "h= a + Q" defined as follows: (*Définit la fonction indicatrice*) indicator[x_] := Piecewise[{{1, 0 < x < \[Pi]/2}}, 0]; (*Semi groupe*) S[x_, t_] := Sum[ Exp[- t n^2] Integrate[x Sin[s n^2], {s, 0, \[Pi]}] Sin[x n^2], {n, 5}] (*controllability map*) G[x_, t_] := indicator[x] S[x, T - t] (*Grammian operator Q*) Q[x_, t_] := (indicator[x])^2 Integrate[(S[x, T - s])^2, {s, T - l, T}] v[x_, t_] := InverseFunction[a + Q][x, t]; (*Test*) N[v[w1 - S[1, T], T] ] It's not working for me because of the expression of "h=a + Q" which is complicatedBest regards, Answer
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Posted 4 months ago
 You can try something like this as long as h has a single value in the inverse domain.Using Sin as an example data = Table[{N@Sin[x], x}, {x, 0, Pi/2, Pi/200}]; invF = Interpolation[data]; invF[1/Sqrt] / Degree (* 45. *) Sin[45 Degree] (* 1/Sqrt *) Answer
Posted 4 months ago
 Hi Rohit, I just edit my question, I specified the expression of the function to inverse! Do you have any idea why it's not working pleas? Answer
Posted 4 months ago
 To obtain proper help, show the h function in code or attached a notebook. Answer
Posted 4 months ago
 ok, I just edit my question. Answer
Posted 4 months ago
 This seems to be the same question as this. Answer
Posted 4 months ago
 Indeed yes, I have just checked it is my partner in this work who asked the question, I will send him a message so that he deletes this message not to repeat the same question. Answer