Mathematica Tutorial: Notebooks And Documents - Wolfram Research

Notebooks and Documents 73Using text strings and functions like Row, you can generate pieces of output that do not necessaroutputthat corresponds to a valid Mathematica expression, but only so long as the expressionis not evaluated. The function Defer maintains its argument unevaluated, but allows it to beformatted in the standard Mathematica output form.Defer maintains 1 + 1 unevaluated.In[14]:= Defer@1 + 1DOut[14]= 1 + 1In[15]:=Out[15]= x = 3The Defer prevents the actual assignment from being done.Defer@x = 3DWhen the output of Defer is evaluated again, which might happen by modifying the output orby using copy and paste, it will evaluate normally.In[16]:= x = 3Out[16]= 3The following output was copied from the previous output cell into an input cell.It is also possible to produce output whose appearance has no direct correlation to how itevaluates by using Interpretation. This method is effectively used by Mathematica whenformatting some kinds of outputs where the most readable form does not correspond well tothe internal representation of the object. For example, Series always generates anInterpretation object in its default output.Although this output displays as y, it will evaluate as x.In[17]:= Interpretation@y, xDOut[17]= yCopying and pasting the previous output will reference the value earlier assigned to x.In[18]:= 2 yOut[18]= 6