Weird behavior of substitution in Mathematica.

Posted by Ilya on Stack Overflow See other posts from Stack Overflow or by Ilya
Published on 2010-03-22T02:33:28Z Indexed on 2010/03/22 2:41 UTC
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mathematica

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substitution

My question is: why doesn't the following work, and how do I fix it?

Plot[f[t], {t, 0, 2*Pi}] /. {{f -> Sin}, {f -> Cos}}

The result is two blank graphs. By comparison,

DummyFunction[f[t], {t, 0, 2*Pi}] /. {{f -> Sin}, {f -> Cos}}

gives

{DummyFunction[Sin[t], {t, 0, 2 *Pi}],  DummyFunction[Cos[t], {t, 0, 2 * Pi}]}

as desired.

This is a simplified version of what I was actually doing. I was very annoyed that, even after figuring out the annoying "right way" of putting the curly brackets nothing works.

In the end, I did the following, which works:

p[f_] := Plot[f[t], {t, 0, 2*Pi}]
p[Sin]
p[Cos]

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