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Mathematica > Core Language > Expressions > Evaluation Control >

Built-in Mathematica Symbol

NHoldRest

NHoldRest
is an attribute which specifies that all but the first argument to a function should not be affected by N.

Prevent N from affecting all but the first argument of a function:

System symbols with the NHoldRest attribute:

Use Part symbolically:

Using N does not affect the specified parts:

The expression works when x is substituted with a list:

Define a function that represents the real-valued root

for positive

and positive integer

Prevent its second argument from being converted to real using NHoldRest:

An exact representation of the cube root of 2:

Machine-number approximation:

47-digit approximation:

Subscript by default has the NHoldRest attribute:

This means that subscripts generally do not change under N:

HoldRest prevents evaluation while NHoldRest only prevents numerical evaluation:

You can prevent both by setting both attributes: