How should I use replace so that
f[x_] := x^2
Replace[f[3], 3 -> 1]
OUT = 9
evaluates to 1, instead of 9? This way, the replacement of the argument is done before the call to the function
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1 Answer
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Activate@Replace[Inactive[f][3],3->1, Infinity]
1
or
Replace[Hold@f[3], 3 -> 1, Infinity] // ReleaseHold
1
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1$\begingroup$ We have had this very question several times before. If you have time would you look for a duplicate? Edit: I found I couple of possible duplicates and linked them above. $\endgroup$ Commented May 26, 2016 at 16:59
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1$\begingroup$ @Mr.Wizard, could not find anything useful in the first 2-3 pages of search results with search terms
Replace,UnevaluatedandInactive. Btw, which search terms did you use to get the links you posted? $\endgroup$– kglrCommented May 26, 2016 at 17:32 -
1$\begingroup$ Thank you for looking! I believe I was using the query
code:"/." code:unevaluated is:answerbut most of the time I feel like stumbling upon the right post is mostly blind luck; this is why I take so much time adding all the Related: links, because I often find things faster by following the network of connected posts. $\endgroup$ Commented May 26, 2016 at 18:12
Replace[Hold@f[3], 3 -> 1, Infinity] // ReleaseHold? $\endgroup$ReplaceAll[Unevaluated[f[3]], 3 -> 1]? $\endgroup$