0.3. Getting info

Every piece of information in Mathematica is associated to a symbol and can be obtained using the ? and ?? symbols (see the command Information in the Mathematica help). xTensor` strictly follows that rule. (In particular, we have explicitly avoided notations based on string input/output which would require a parser, much restricting the capabilities of the user.)

In[53]:=

? DefManifold

In[54]:=

??ERROR

ERROR[expr] is an expression where an error has been detected. ERROR is an inert head with a single argument.

Attributes[ERROR]={HoldFirst,Protected}
InertHeadQ[ERROR]^=True
Info[ERROR]^={inert head,Generic head to wrap expressions with errors.}
LinearQ[ERROR]^=False
PrintAs[ERROR]^=ERROR
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