CODEWITHSUNDEEP
functionwolfram-mathematicaderivative
user1676921
user1676921

Reputation: 83

Mathematica clear a function's derivative definition

I defined the derivative of a function in Mathematica without defining the function itself, i.e. I have a function definition that looks like this:

y'[x_] := constant * f'[x].

I can't figure out how to clear it out. If I use Clear[y'] or `ClearAll[y'], I get an error message:

ClearAll::ssym: y' is not a symbol or a string.

Clear[y] and ClearAll[y] do nothing to remove the definition of y'.

Any ideas on how I can remove the definition of y'?

Upvotes: 6

Views: 2083

Answers (2)

image_doctor
image_doctor

Reputation: 501

This should do what you want:

y'[x_] =.

See Unset. Also see this question for related information.

Upvotes: 5

Chris Degnen
Chris Degnen

Reputation: 8655

You can use Remove[y]. For a function name f' is unusual syntax, but it does appear in the documentation for derivative: http://reference.wolfram.com/mathematica/ref/Derivative.html

The derivative name form seems to present a bit of a problem for Information (??), which would usually show attribute information.

y'[x_] := constant*f'[x]
y'[4]
??y

constant f'[4]

Global`y

Remove[y]
??y

Information::notfound : Symbol y not found. >>

y'[4]

y'[4]

But oddly, (and nothing to do with the derivative name form):

Information[y]

Global`y

There is some deeper information about Remove here: https://mathematica.stackexchange.com/questions/4921/what-is-the-story-with-removed-symbols

Upvotes: 1

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