Feeding a mathematical function as the argument of a Function

Question

I have the following Function:

Testing[g[x_], y_] := Module[{s = x, t = y, c }, c = s + t ; c]

Which I am just trying to get to work before doing my actual application. It should accept a function g[x] and do stuff with it.

As a test, I try:

f[x_] := x^2;
Testing[f[x], 4]

But it just returns

Testing[x^2, 4]

which means that it does not understand what I mean...? What is the correct syntax to feed a mathematical function into my Function?

Testing will only work for something with head g while f[x] evaluates to Power[x,2]. — Kuba, Commented Nov 23, 2016 at 16:02
If you want it to accept a function in the form g[x], but with any kind of name (instead of g specifically) and any kind of variable, then you should use Testing[g_[x_], y_] := .... Moreover, you should probably make Testing HoldFirst to keep the function from evaluating too early: SetAttributes[Testing, HoldFirst] — Sjoerd Smit, Commented Nov 23, 2016 at 16:34

Coolwater · Accepted Answer · 2016-11-23 16:09:46Z

2

As I understand you, what you want is that c becomes x^2 + 4. This gives you that polynomial with an anonymous variable instead of x:

Testing[g_, y_] := Module[{s = g[#], t = y, c}, c = Evaluate[s + t] &; c]
f[x_] := x^2
Testing[f, 4]

4 + #1^2 &

answered Nov 23, 2016 at 16:09

Coolwater

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