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Find the conditions for which a singlevariable, realvalued function is differentiable
ResourceFunction["FunctionDifferentiability"][f,x] returns the conditions for which f is differentiable with respect to x. 

ResourceFunction["FunctionDifferentiability"][f,{x,n}] returns the conditions for which f is ntimes differentiable with respect to x. 

ResourceFunction["FunctionDifferentiability"][{f,cons},x] returns the conditions for which f constrained to cons is differentiable with respect to x. 

ResourceFunction["FunctionDifferentiability"][{f,cons},{x,n}] returns the conditions for which f constrained to cons is ntimes differentiable with respect to x. 
lhs == rhs  equations 
lhs > rhs , lhs ≥ rhs , lhs < rhs , lhs ≤ rhs  inequalities (LessEqual,…) 
Compute the conditions for which a given function is differentiable:
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Compute the conditions for differentiability of a function subject to a constraint:
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A function that is differentiable for all real numbers returns True:
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The following function is oncedifferentiable everywhere but not twicedifferentiable at x=0:
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FunctionDifferentiability has the attribute HoldFirst, enabling calculations such as the following:
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