Mathematica clears the definition of a derived function

Question

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 clean it. If I use Clear[y'] or `ClearAll [y'], I get an error message:

ClearAll::ssym: y' not a character or 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' ?

+4

user1676921 Sep 17 '12 at 7:34

2 answers

image_doctor · Answer 1 · 2012-09-18T15:36:52+0000

This should do what you want:

 y'[x_] =.

See Unset . Also see this question for related information.

Chris degnen · Answer 2 · 2012-09-17T08:27:30+0000

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

The derivative name form seems to be a small issue for Information (??) , which usually displays attribute information.

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

f 'constant [4]

Global`y

 Remove[y] ??y

Information :: notfound: The symbol y was not found. →

 y'[4]

y '[4]

But strange (and has nothing to do with the derivative name form):

 Information[y]

Global`y