BUILT-IN MATHEMATICA SYMBOL
AtomQ
AtomQ[expr]
yields True if expr is an expression which cannot be divided into subexpressions, and yields False otherwise.
- You can use AtomQ in a recursive procedure to tell when you have reached the bottom of the tree corresponding to an expression.
- AtomQ gives True for symbols, numbers, strings, and other raw objects, such as sparse arrays.
- AtomQ gives True for any object whose subparts cannot be accessed using functions like Map.
Test if an expression cannot be subdivided:
| Out[1]= |  |
| Out[2]= |  |
Since it is not an atom, its parts can be extracted:
| Out[3]= |  |
This is a number that is an atom:
| Out[4]= |  |
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