Derivative operator not working for the function defined as F[0, x_] = Sin[x]

Question

I need to define a sequence of functions $$ F_0(x), F_1(x), \dots $$ where each function $F_{k+1}(x)$ is defined using $F_k'(x)$. For simplicity let's assume that $$ F_{k+1}(x) = F_k'(x). $$

I'm using the following (not working) Mathematica code:

F[0, x_] = Sin[x]
F[kp1_, x_] := F[kp1_, x_] = With[{k = kp1 - 1},
  Derivative[0, 1][F][k, x]
]
F[1, s^2]

The code gives $RecursionLimit::reclim due to

Derivative[0, 1][F][0, x]

is not evaluating and I have no idea how to fix that.

Actually I can introduce dummy variable and use D instead of Derivative

F[0, x_] = Sin[x]
F[kp1_, x_] := F[kp1_, x_] = With[{k = kp1 - 1},
  D[F[k, y], y] /. y -> x
]
F[1, s^2]

This code works flawlessly, but in my actual problem there's a lot of variables and introducing new variables will make a huge mess, so I would like to stick with Derivative operator.

Have you seen this? – J. M.'s missing motivation Oct 05 '16 at 17:46 — J. M.'s missing motivation, Oct 05 '16 at 17:46

score 2 · Accepted Answer · answered Oct 05 '16 at 21:59

2

Your second method can be done with an "anonymous" substitute for y, namely, Slot[1]:

ClearAll[F];
F[0, x_] = Sin[x];
F[kp1_, x_] := F[kp1, x] = With[{k = kp1 - 1}, Evaluate[D[F[k, #], #]] &@x]

F[1, s^2]
(*  Cos[s^2]  *)

answered Oct 05 '16 at 21:59

Michael E2

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score 0 · Answer 2 · edited Oct 05 '16 at 18:49

0

Try this --- I suppose that the initial function is Sin[x]

F[x_][0] := Sin[x]
F[x_][n_] := F[x][n] = D[F[x][n - 1], x]

edited Oct 05 '16 at 18:49

march

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answered Oct 05 '16 at 18:43

cyrille.piatecki

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1

What if x is not a symbol? – uranix Oct 05 '16 at 19:30
Give an exemple – cyrille.piatecki Oct 05 '16 at 19:44
Example F[s^2][1] – uranix Oct 05 '16 at 19:46
I dont understand: should one make the integration on s ? If it is the case, the formula works in the same way F[s_][0] := Sin[s^2] F[s_][n_] := F[s^2][n] = D[F[s^2][n - 1], s] – cyrille.piatecki Oct 05 '16 at 19:54
Of cvourse I should have written derivation in place of integration – cyrille.piatecki Oct 05 '16 at 20:15

Derivative operator not working for the function defined as F[0, x_] = Sin[x]

2 Answers2