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3.1.9 Advanced Topic: Controlling Numerical Evaluation

Attributes for controlling numerical evaluation.

Usually N goes inside functions and gets applied to each of their arguments.

In[1]:= N[f[2/3, Pi]]

Out[1]=

This tells Mathematica not to apply N to the first argument of f.

In[2]:= SetAttributes[f, NHoldFirst]

Now the first argument of f is left in its exact form.

In[3]:= N[f[2/3, Pi]]

Out[3]=